Last June I did some shopping in a whisky shop in London and I had quite a few severe issues with the Customs, because I claimed the tax refund. In order to do so, in Heathrow, they forced me to carry the whisky bottles as hand luggage.
I will fly to Scotland next month and I hope that the situation will improve, since I intend to bring back some bottles with me. Carrying bottles in check luggages has not been a problem so far, with only 1 exception. The cork of 1 bottle went loosed and the whole bag was then flavoured with Glenmorangie whisky. In any case, please make sure that your bottles are well packed, with bubble paper.