[Dave]

Although this link is aimed at sellers, it gives the buyer a good insight to the levels of protection you are offered (Tx to PeteT for link)
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The Office of Fair Trading: Distance Selling Regulations

If you sell goods or services to consumers by:

the internet
digital television
mail order, including catalogue shopping
phone
fax
then you need to know about the Consumer Protection (Distance Selling) Regulations 2000.

The key features of the regulations are:

you must give consumers clear information including details of the goods or services offered, delivery arrangements and payment, the supplier's details and the consumer's cancellation right before they buy (known as prior information)
you must also provide this information in writing
the consumer has a cooling-off period of seven working days.