To see the best (and worst) times to visit, please read our reviews of our recommended places to stay
Note: flight, boat, train and bus timetables change constantly, and airlines come and go, so please do not rely solely on this information for your travel planning. Check with relevant companies, or a flight search engine like Skyscanner, first.
London now has 5 airports worth considering, depending which part of the city (or surrounding area) you are heading to:
Heathrow (25km west) is served by hundreds of airlines (including most national carriers), and is the busiest passenger airport the world. The Heathrow Express train whisks you into London Paddington in about 15 minutes but it's quite expensive; a much cheaper and slightly slower alternative is the Heathrow Connect (25 minutes into Paddington). There are underground (Tube) links into London too, as well as coach services (mostly National Express) to cities across the country.
Gatwick (50km south) is the 2nd busiest airport, and the hub for most charter flights ex UK, as well as some low-cost carriers. The Gatwick Express train shuttles straight into London Victoria in about 30 minutes; there are stopping trains too (slower and cheaper), which also serve the south coast (Brighton etc) and south west (Reading etc).
Stansted (50km northeast) is London's 3rd airport, and very popular with low-cost carriers, including easyJet and Ryanair etc. The Stansted Express train runs into London Liverpool Street in 45-60 minutes, stopping at various stations en route; and there are coaches via northeast London to Victoria, as well as trains direct to East Anglia and the Midlands.
Luton (50km north) is London's 4th airport, used by an increasing number of low cost carriers, including easyJet, Ryanair, Air Berlin, Norwegian, Transavia, Air Italy, Wizzair etc. Transport connections into London and other towns are less good.
London City (15km east) is a small single-runway airport handy for city-centre to city-centre flights, and popular with business passengers. It has excellent links into the City, London's financial centre.
Bristol is the busiest airport in the south west. It's a regional hub for easyJet and Ryanair, who between them cover most of Europe; it's also served by some minor European airlines (Brussels Airlines, KLM Cityhopper, OLT from Hamburg) and transatlantic carriers (Continental).
Exeter is a major hub for Flybe, which has routes to/from most European countries, and also has links to the Scilly isles with Skybus and to Canada with Air Transat. If you're heading to Devon or Cornwall, it's probably the best placed airport.
Newquay is a small but growing airport in Cornwall, with links to the Scilly Isles with Skybus, and to Spain with Ryanair, as well as a few other links.
Southampton is a good alternative to Gatwick if you're visiting the south coast from Spain, France, Germany or Ireland, all of which are served by Flybe, as are various UK airports.
Birmingham is the regions' busiest airport, and is used by Flybe (a scattering of European destinations), Monarch (a charter/scheduled carrier serving classic holiday/Med destinations), Thomsonfly (ditto), Ryanair (but not a major hub of theirs) and a few national carriers.
East Midlands is well placed for Derby, Leicester and Nottingham, which are all within 30km, and is served by Ryanair and various charter companies.
Oxford has a small airport with sporadic domestic/shorthaul connections - see Oxford Airport for the latest - as well as the option of private charter flights.
Norwich is served by BMI flights from Aberdeen, Flybe flights from Edinburgh, Exeter, Manchester, Geneva, Guernsey and Jersey, and KLM flights from Amsterdam. Alternatively, fly to London Stansted (see above).
Cardiff is the country's only international airport, and a handy entry point for south Wales. It's served by Flybe, Thomsonfly and Thomas Cook, with the majority of routes serving Mediterranean holiday spots (Alicante, Palma de Mallorca etc) and nearby city breaks (Amsterdam, Edinburgh etc).
Another option for southern Wales is Bristol - see above.
For northern Wales, Liverpool and Manchester are the nearest airports - see below.
Options include Liverpool, Manchester, Blackpool, Leeds/Bradford, Humberside, Newcastle, Durham Tees Valley and Robin Hood Airport (Sheffield/Doncaster). Most of these operate charter flights to popular European destinations, domestic flights to major UK airports, as well as connecting flights (via Amsterdam, Frankfurt, Paris etc) to the rest of the world. Try the following airlines for the airports shown (B=Blackpool, L/B=Leeds/Bradford etc): Jet2 B, L/B, M, N
KLM DTV, H, L/B, M, N
Eastern Airways H, L/B, N, DTV, M
easyJet RHA, L, N
Ryanair B, L/B, N
SN Brussels Airlines M, N
It can take longer than you think driving from southern England to Scotland, and driving around Scotland, so consider some of these options: Glasgow International is the country's busiest airport, with links to most of Europe and some long-haul destinations. Airlines include easyJet, charters like Thomsonfly, Thomas Cook, plus a smattering of national carriers (including British Airways from London and Logan Air, which codeshares with Flybe/British Airways for Scottish regional flights).
Glasgow Prestwick (45km south) is a major hub for Ryanair and is also used by Wizzair. Trains and coaches link to the city centre, but not very frequently.
Edinburgh is the country's 2nd airport, with good connections across Europe. Airlines include easyJet, Ryanair, Flybe, and a smattering of national carriers (including British Airways from London).
Aberdeen has good connections to English airports with Flybe and Eastern Airways, and a few links to the Med, northern Europe and Scandinavia.
Inverness is handy for the north, with routes from England (easyJet, Flybe, British Airways), Ireland (Aer Arann) and Scottish regions (Logan Air, which codeshares with Flybe/British Airways).
If you want to hire a car to see this green and pleasant land, see our car rental recommendations. Don't forget to drive on the left, and to observe speed limits (70 miles/hour on motorways, 30 miles/hour in built-up areas) - as there are increasing numbers of roadside cameras.
If driving into central London, you will need to pay the daily 'congestion charge' (if hiring a car, ask about this in advance).
British Airways flights connect the major cities (London, Manchester, Leeds, Newcastle, Glasgow, Edinburgh etc), while budget carriers Ryanair and Easyjet are also useful if travelling from the southeast (Stansted/Luton) to Scotland (Prestwick, Edinburgh) or northeast England (Newcastle).
For cheapest fares, try and book your ticket as far in advance as possible, using thetrainline.com or nationalrail.co.uk. Finding the cheapest fare can be astonishingly complex - it may even be 2 singles. Some routes, especially down the west of England (e.g. Bristol to Leeds / Newcastle), are run by Virgin Trains. If your train arrives over an hour late, you are normally entitled to compensation, but you will have to fill in a form with details and tickets, and give a UK address for the refund.
GETTING AROUND LONDON
By Tube (Underground)
Get an Oyster card at any tube station - it will cost you a few pounds but you will quickly recoup this, as journeys cost are almost half the normal cash fare (the shortest journey now costs over £3 if you pay cash) (in 2009). If you are staying for a while and have a UK bank account, you can arrange an auto top-up when your fare credit gets low, using the Oyster website.
By day, hail a black cab - the distinctive black car which seats up to 5, and where journeys are metered. On busy evenings and late at night, it may be easier to call a minicab (ordinary car, with licence) - in which case you should check the fare before setting off.
There are still some red double decker buses, though they are no longer not the classic, jump-on 'Routemaster' model which made them famous. Sitting on the top deck is a great way of seeing the city. There are also some night buses on popular routes (preceded by 'N') if you need to get home cheaply after about 11.30.