I have no idea either, but I reckon postage would be very expensive! Parcelforce might be the best option - up to 10kg weight is about £17 for Express 24, or £13 for Express 48 plus extra if you want insurance. If you go on their website you can get a quote by putting in yours and sellers postcode and the weight. I just did it for 10kg to get that price and I doubt it is anything like that heavy
I think anything betweeen 2kg and 10kg is the same priceandit will be more than 2kg.