Tenerife is one of the main islands of the Spanish archipelago off the coast of North Africa. The Canary Islands have long been a popular holiday destination thanks to their warm (but not excessively hot) weather most of the year round. There's certainly no shortage of cheap flights to Tenerife either.
Flights to Tenerife from the UK depart from most of the country's major airports. There certainly won't be any reasons why you would need to get a flight transfer either. Ryanair offers cheap flights to Tenerife from London Luton, London Stansted, Liverpool, Derry and Birmingham. Easyjet offers flights from Bristol and Manchester. There are also package tour operators such as Thomas Cook which provide flights from some of these airports and others. You can find out more at flythomascook.com.
With regards to cheap flights, it is usually better to book well in advance. The prices of budget airline flights are often excessively high if you book only a matter of days or a few weeks before. Booking several months in advance, by contrast, will likely land you an absolute bargain. To find the cheapest flights to Tenerife as well as anywhere else in the world, check out opodo.co.uk or skyscanner.co.uk to compare prices.
Things are slightly different with package tour operators, which are often the best place to turn for last minute deals. Many package holiday companies organize trips to Tenerife and your local travel agent or online travel agent should be able to update you with the most recent deals. Last minute deals tend to be limited however, and you may not be able to find a convenient departure point.