Hopefully the UK rules will be a bit kinder to you than the Aussie rules would be.
Here you'd need a CPL(H) to start. You can get a credit on the flight time for your licence (minimum 60 hours training instead of 105), and would only need to sit the four helicopter-specific CPL theory exams. But then you'd need to have at least 360 hours helicopter, before doing the 40 hour instructor course. R22 with instructor is around $A400-$A450/hour (£190-£215/hr) at the moment, so you can do the numbers. No quick, easy or cheap way unfortunately.
I'd be interested to see what the UK answer is ...