Cabair and Trent Air Services at Cranfield before them - sizeable fleets and operating for many years (Cabair for more than 30) - size and longevity provide no guarantee of protection.
If you are intending to go down the modular route, a PPL is a necessary and hopefully enjoyable part of the process. If an integrated path is your plan, a PPL is largely a waste of time. Certainly a few lessons to give you a taste would be a good idea but habits and lack of standardisation can present obstacles during integrated CPL training that could be avoided. If you are seeking a place on a selected or tagged training programme (e.g. BA FPP) a PPL might be barrier to selection.
As far as integrated schools are concerned, the sad truth is that some provide a connection to potential employers that you would otherwise have to generate yourself - you could be an exceptionally talented and good all round modular graduate who struggles to make an introduction whereby a weak integrated student who just manages to hang on through the course gets lucky when the local airline recruiter is passing through the school.
I agree with others here from the point of view that a PPL does show interest and is a fun thing to do but hopefully now you have your Class 1, do some more research and determine a path to focus on. At 17, you have your whole career ahead of you but the decisions you make now will determine the course it takes.