Parts for brake job on car under extended warranty

I have a Megane 3 2010 model and took it to a Renault dealer for a check up, they told me that it will soon need new front pads and discs and new rear pads. I checked and I agree with them. They quoted £192 to do the job. As the car is under extended warranty I thought I would do the job myself but thought that I should really use genuine Renault parts. The best price I can find was £220 ! so looked at Eurocarparts and their price for Pagid parts was £122 . So

1. Do I affect my warranty if I use non Renault parts?

2. Where should I be looking for Renault parts at a reasonable price?