Not copies, but you may get problems with warranty. Many manufacturers will only honour warranties if it was purchased from a local authorised dealer (i.e. from within the UK). Grey imports you'd have to return to the seller. You'd need to check their returns policy, including who pays the postage.
Plus, you may get stung for import duty and VAT. Some of these grey dealers dodge paying the correct duty (hence their low prices) and you could get stung.