There are some really cheap flight deals to Hong Kong at the moment. Virgin and Air New Zealand have already got current deals going but at around the £320-£350 mark. Using Orbitz, there are some really cheap flights deals with Quantas to be had. For example:
2nd May - 11th May: £283
26th May - 4th June: £283
8th June - 15th June: £283
Note - these are priced at $400, so the price may vary depending on what your bank charge you.