Chrisallen
Check out what is required for foreign licence conversions on the UK CAA website under LASORS.
Regarding places to train, can't say much about Oz, but South Island NZ is certainly a challenging place to learn as there are some very solid mountains to avoid and the weather can actually be worse than the UK.
What do you want to do with your licence? If you want to get a CPL and make a "living" from it, then it's worth considering remaining in one country to get to know the industry. I'm not suggesting it's the best or only way (there are a million and one paths taken to date), but it's a good start.
If you want to leave it at a PPL (which 99% of CPL holders would suggest!), then get yourself down-under, have a great experience, and learn how to drink fizzy !!!!ty beer.
Try these schools for a start, Wanaka Helicopters, Nelson Aviation College. Good mountain flying, awesome scenery and scarey women.
You've got about 60-70 hours to do for a PPL, rough guide of 2 hours a day, 4-5 days a week allowing for weather if you're doing it full time.