Murphy Beds are an American company, and their web site includes a "Build a Bed on Line" section which is well worth taking a look at. I believe that their distributor in the UK is Murphy Wall Beds UK. By the way - they aren't cheap.
The Wooodfit only comes in 4ft 6in (std. double size) and it's not that much cheaper than the Murphy one. Hafele do a similar item called a double foldaway bed and a lower cost unit, but they also list a single foldaway bed. The Isaac Lord Create-a-Bed units are considerably cheaper, have you ever used one? Any good? I've used a Murphy in the past at a customer's request (they were American) and they are substantial and well made. Main thing is to ensure that they are properly bolted down (through the floor).