I don't know if you can validate over there, you will most likely have to write the exams again and do a flight test.
Oxford is great, I did my JAR ATP there and had a ball. The course is 9 months full time and costs about 6000 pounds
You can opt for distance learning, buying the books will cost you a couple thou, but the exams are much harder than the SA ones so unless you have brains its best to go to college. You will have to get accommodation etc while you are there so there are the usual added costs.
If you have good hours I don't see any train smash in getting work, apart from permit issues. If you have low hours - don't bother, there are literally thousands of them there looking for work, and if you can't speak french, dutch, german etc you are pretty much restricted to the UK, and lets face it, who wants to live there.
Best of luck.