I was faced with a similar situation - my stay in the UK was only ever going to be ~2 years so the balancing act was perhaps a little different.
I agree with the comments and sentiments above.
What I opted for was to keep crediting to QF - and cringing whenever I got 5 status credits and 100 miles for a very shorthaul flight. With hindsight I suspect that I might have been better off swapping to BA - although it would have been a right pain to not be able to use the priority security lines at T5 and then have to wait around at the door of the lounges whilst they see whether you are eligible to enter.
I did open a BAEC account for bits and pieces accruals - tesco, cash back site (topcashback - although this is no longer worth it) various other bits and pieces. I managed to accumulate a number of points quickly and easily - which have come in very handy on more than one occasion (particularly for last minute flights).