Yes, under distance selling regulations (UK Consumer Contracts 2014) the buyer has the right to cancel the purchase up to 14 days after receipt of the goods and return them (in original condition) for a full refund, including original postage costs. They don’t need a reason, they can just change their mind. Unless you state in your policies (or Folksy policies) that the buyer is responsible for return postage, you’d also have to refund these. Folksy does state this in their policies, so return postage is the buyer’s responsibility (useful to note this if you sell from other sites, as they don’t always have a standard policy). Custom-made/personalised items are exempt, and certain other items for hygienic reasons are too, but not made-to-order items unless they have been too customised to re-sell.
They are supposed to contact you before sending it back, but if they return it within the 14 days, I suppose that’s acceptable.
If the goods are faulty or not as described, they have much longer to return them and the seller is responsible for return postage.