Perwazee
I think that you will find that you need to take the JAR ATPL written exams
That will be a significant obstacle requiring considerable time and a a little money. You could do it distance learning from US (checkout Bristol Groundschool costs).
The flying should be a breeze with your experience (mostly at discretion of head of training) - You must attend an approved training providers course (bit of a racket and more cost).
You will find all of the info in the CAA bible "LASORS" which is available on-line at caa.co.uk
There will be the frustrating cultural and training differences to overcome "you have done that wrong!" , "we don't do it like that" etc etc and dare I say it some people might even be slightly prejudiced ?
Anyway if you have no experience of the CAA / JAR system I would say FORGET IT !!!! Beaurocracy, cost, innefficiency and monopoly practices - all very frustrating.
On a more personal note I am planning to go the other way and am wondering how bad the schools can be over in the US ? (i HAVE YOUNG CHILDREN).
Your flying job sounds good and before you give that up I would think long and hard .
Best of luck and hope this helps.