Gumaark,
Only you can answer those questions. Do you have a spare $50,000? That is approx what you will need. The exam credits aren't valid indefinitely, you have 3 years from the first sitting to get the IR done. You had better check what the latest state of play is with exam credits too.
Only you can decided what you want to do with your career.
Have you been to the UK? Before I decided to leave Australia I had a holiday here. You may not like the place.
See the country before making a very expensive move.