It won't make any difference to an airline where you do your PPL via the modular route. Schools trying to flog you a full ATPL course come up with this all the time, don't fall for it. Several students who I instructed ATPL ground school to on the modular system have gone on to successful careers in major airlines. One went from student pilot 4-5 years ago via a smaller UK airline is now RHS for Jet 2 another is at Virgin. It's all about the right attitude & being in the right place at the right time. Going locally for your PPL makes a lot of sense and you can cut your costs & save it for the more expensive flying to come.
However, airlines do tend to prefer to see all the CPL/IR flying done at one place & for the sake of consistency I would agree, but it's the MCC at the end that probably counts more than anything. The most important thing to do before you commit is to get a Class One Medical BEFORE you start training, though you won't need it for a PPL (class 2 sufficient) but without it no CPL.