Rodney said:
If it's just for a retail site and you're making a return policy, it doesn't seem like it needs to be a big legal document. But I'm not 100% sure of the laws in the UK about this.
In Australia, I'm fairly confident the UK, and I would have thought the US but am not sure... a return policy is to a certain extent unnecessary. There are consumer protection laws in place which put certain requirements on retailers. Your return policy isn't really a contract, so much as informing people of what their statutory rights are.
It's a good idea to inform people since they often don't know and it raises buyer confidence, but you're not creating new legally-binding rules for them so much as doing what is already legally required of you. The main thing is to be sure you're not offering less than is legally required so you can't be seen as restricting the customers' rights.
Rodney said:
If you are concerned about the legality of it, I would suggest contacting a lawyer.
This is, of course, the most important thing, as always.