I'm travelling to Hong Kong next month (returning to Thailand) and have one and half blank pages in my passport, whilst I have a multiple re-entry visa for Thailand already I'm guessing that I'm going to need a new one?

If so how long does the new, HK application, process actually take, they mention to allow 4 weeks on the website.. is that accurate?

I don't know how long they take in Hong Kong but last October I got my new passport via the Consulate here in HCMC and it took 13 days, total not working, from handing it in to receiving the e mail to say the new one was ready for collection. So I'd hazard a guess 9 days in HK but I've no back up for that. The website tells you what to allow, what it actually takes is dependant on numbers of applications.

Btw that service from HCMC was back when the Consulate still did all the sending to HK for you, at a price of course, but now they've sunk to the level of service previously reserved for the Thai based sexpats (only joking) so from now on we have to do the posting .

How to apply from Thailand (Renewals) says to allow 4 weeks. Anecdotal evidence suggests it usually takes about half that.