Modular training
It should be possible to manage all the training in the UK through the modular route with 50k. For example Air Service training at Perth in Scotland aim for the entire course for under 50k including hour building but excluding the MCC, exams/test and licensing costs. If your planning for bush flying to begin with then you won't need the MCC at that stage anyway. I believe Stapleford are also very competitively priced as I'm sure many other modular FTO are. However these costs are all based on minimum hours so reserve funds is a must not only for additional hours but the exam/test, licensing and living costs to name a few.
No personal experience of the FAA training or ATP but an FAA licence would limit your future job prospects within Europe should you decide to return to Europe. Have you thought about doing the EASA/JAA licence in the US? Dont know the costs or detailed rules but plenty schools offer this, I think having to do the IR in Europe but don't quote me on it.
Final note, plenty of other guys have been in your position and asked much of the same questions all available on this forum.