really, what are you working on? do you happen to have any co workers or friends that are foreigners? so you can hang around with them a bit more and practice.
I am not saying heading to UK isnt such a great idea, but i think there are lots to consider. your family, work and such. to make improvements on orals and grammars, you have to completely lock yourself into their world and culture. really that s the only and most effective way of learning, dwell yourself in it.
you also might want to consider which type of English you want to get into, is it the American style or the Typical UK style, cause they both have different accent and also different wordings.
o, there is this Geoexpat site where foreigners working or living in HK at the moment gather on this site, they have function from times to times, you can join some them and see what you think.
and if u still really want to head to UK then i would suggest help from the British Council, thats where i ve found my school. surely it helps a lot. take care.