Cheapest I can see, Ebay and Amazon prices are £64.99, I'm tempted in case we get bad dose of snow :)
Confidence Home Pro Bike Trainer. Never miss out on your cycling time again with the Confidence Home Pro Bike Trainer - no matter the weather! Converting your bike into an indoor cycling fitness machine, even if it's raining cats and dogs outside, your trusty two-wheeled companion will still be there for you with this innovative exercise tool converter. Featuring up to 7 level of adjustable magnetic resistance, you get your workout on and burn off the calories in no time, all without leaving the comfort of your own home. Easy storage and transportation with its clever folding design, this great Bicycle Trainer is the ideal item for someone who doesn't want the weather dictating when they have their two-wheeled time! Feature: Applied to Bike with 26"-28" wheel. Foldable design for easy storage. Riser block is included .7 level of magnetic resistance .Dimension: 21.5" x 18.5" x 14.4" .Weight: 6.9kg .Max loading: 150kg.
Read more at http://www.tesco.com/direct/Confidence%20Home%20Pro%20Foldable%20Indoor%20Bike%20Turbo%20Trainer%20+%20Handlebar%20Adjuster/637-4896.prd#PISUUpULzUQEQyr5.99