Car Licences for foreigners of first world nations ie BRIC etc that hold a valid HKID card, can transfer their overseas licence with attached endorsements ie motorcycle/car here in the HKG.
Technically, all you need to drive/ride in HK as a non resident on a tourist visa is, an international drivers licence attached to your UK one...
You don't just need a HK licence to hire a vehicle here, a valid international licence and a credit card will suffice....Just like majority of Europe or Australasia/America etc etc
Also, when you do become a legal HK resident, HK law stipulates that, you can only drive on an international licence for a period of not longer than 6 months of becoming a resident. After that, you must convert your overseas licence to a HK issued one, which can be done at any licencing branch of the HK Transport Department...