Sorry to contradict BelArgUSA, but there is plenty of parking in HK if you know where to look. Free parking is certainly in short supply, and you don't get free parking at the shops anywhere near the urban areas (different in the suburbs), but compared to parking inner city elswhere in the world, parking is reasonably priced.
Many places are HKD15-20 per hour, some cheaper and some a little more (HKD25 per hour) if near the busier CBD areas.
You don't need a car in HK unless living outside of Kowloon/ HK Island/ Discovery Bay, but even living in those areas, it's nice to have the freedom of jumping in the car and driving yourself somewhere out of town, or even going to the grocery store and putting your shopping in the boot is something that you may appreciate after a few years of piling into the back of a taxi, while burdened with a dozen shopping bags.
Granted, you can get most things delivered (including groceries), but there's a certain novelty element to putting the groceries in the boot!
As 404 said, it's very easy to convert your UK licence. Good luck.