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Spot on Themas. I went to my local cab and it really depends upon whether or not the agreement is 'regulated'. If it is, the chances of cancelation are very remote. Cooling off periods were instituted due to the increase in 'doorstep' sales and sales away from the sellers palce of business. When an agreement is signed by both parties 'on the sellers premises', the contract is binding. DFS seem to have stitched this method of selling their products very well - unsurprisingly! as their sales technique is based on this framework, therefore legal loopholes are extremely rare.
In hindsight though!!!! before signing the contract, it may be worth requesting that you take a copy of the contract 'home' to consider the small print, then, (if you still want to go ahead with the purchase), return next day with the signed contract. In this way the contract has not been endorsed on the sellers premises...! However, DFS, etc. would probably have anticipated this course of action and not allow you take the contract off their 'patch'.
Anyway, thanks to all for their replies and kind regards.