vincente, i envy your linguistic abilities. Both my parents are from hong kong and I can only speak and read and write basic cantonese and am even worse at mandarin.
Yes, it would be a great idea to move to hong kong, as you have the "lingo" but do it only if you like it. Furthermore, you could do what your dad did: spend a couple of years there and then move back to the uk to work here. However, even if you dont go to hong kong, i reckon you will stand a good chance of getting a job in whatever interests you her in the uk. As you said, china and hong kong are growing rapidly and the uk will want to exploit that fact so your knowledge of all these languages will certainly be in demand here too.
If i could speak mandarin and cantonese fluently, I would rather stay put in the uk and look for a job that probably allows you to travel to china to work because in my opinion, the uk is still better.
But whatever you decided to do, good luck with it and have fun in Hong kong, it is a very nice place.