Just received a reply from a company in London called Excess-Baggage.com. Seems they specialize in moving personal sffects from New Zealand and Australia to UK and vice versa via air and sea freight. They quoted me 128 GBP for a 25 kg bag (about $207). I can drop off and complete the paperwork right at Heathrow. Looks like the way to go. Thanks again to BDL and all who resonded as it saved me hours of legwork.