Yes.
If you were simply relying on your right to return the goods under the Consumer Contracts Regulations (which you could use whether the product was faulty or not), you'd have no right to expect the seller to pay for your p&p.
However you're returning the goods under the Sale of Goods Act and a customer should not be left at a disadvantage (financial or otherwise) through such a return. For example, if you have to make a 50 mile round trip to return a recently-purchased faulty item to a retailer, you're entitled to demand your petrol money from him. Similarly, you can claim for p&p. (Although, in reality, there's probably no much you can do if he refuses as it wouldn't be worth going to court over the matter).