Yeah not a bad one idea, £200 lost is a lot better than 3% over 4 years!I don't believe so - when you order online you have to put the card details for the £200 deposit first. Even you order from a showroom you'll order online anyway.
I *guess* you could order anyway, and then if you don't like it you can cancel and try to get the deposit back. Lots of people mention here that you can resort to the Consumer rights and the Distance Act, but try to search on the forums.