You mention three well-trodden routes:
Modular, Integrated and USA.
Integrated is the most expensive by far. Modular in the UK can be done for £45-£50k and gives exactly the same licence. Then there's the US route, which is by far the cheapest - if you know what you are doing. The US route makes the most sense of you commit to it - meaning get FAA certificates and work as a flight instructor to 1500 hours. The advantage of the FAA system is that you only need 100 hours in powered aircraft, which opens the door to a lot of cross crediting and some very very cheap flying.