I assume you (Redbarron) are flying to/from HKG. I do that route frequently and I'd recommend using the airport post office to mail any holiday purchases home if you are likely to go over your checked weight limit. Its open every day 8am-8pm (5pm sundays) and its pretty cheap to send a parcel to the UK (about £15 for a 3kg packet express airmail).
You can find out all you need to know at
Hongkong Post ????
Happy travels!