The renewal is annual, and costs around £80-90.
Doing a PhD at Bristol it may be worth popping over the Bristol Groundschool to see Alex Wittingham. They only do distance learning, but he will know the various routes and I would trust him to be as impartial as anyone can be in his position. Alternatively I am happy to chat over a beer in Bristol if you like as I am often there (my girlfriend is also doing a PhD at Bristol). I work for Bournemouth Commercial Flight Training but of course a lot of the advice I can give would apply to any school.
Visit a variety of schools (there are 4 down here if you visit Bournemouth!) and discuss different routes before you decide. Assuming you choose modular then I suggest you do not commit yourself to more than one module at a time - once you have started groundschool for example you may be in a better position to judge CPL flight schools, especially if your groundschool offers flying.