You wrote that you will wait about four years before you enroll. Hopefully four more years of maturity and research will equip you with what you need to make your own decisions.
Right now, you seem very insistent that someone give you the answer right now, for what you should do four years from now. Some of the schools might not even be in business by then. What is the rush? This is just 16 year old impetuousness and it doesn't belong anywhere near a £50K decision!
I recommend that you read Pprune for about three months and then you'll have a much better idea how to proceed without begging to be spoon fed a decision. Start with the sticky threads. Right now you don't even know the difference between modular and integrated courses and until you know a bit more, your questions will make you look pretty naff, though you probably won't even know that.
Modular courses give you full credit for a PPL, as you can't even start one without it. If you take an integrated course, the rules allow the FTO to credit up to 40 hours, but they decide how much to credit. Oxford gives no credit to PPL holders who enroll on their integrated APP First Officer course and full credit to those who enroll on the modular Waypoint course. The most credit I have ever seen an FTO allow on their integrated course is 15 hours credit.