Best way to transport luggage on bike?

Hi guys and girls,

I will be traveling from Nimes to Nice by bike with my brother in mid August. I've routed out our way and estimated It'll be around 230 miles over the course of 2 days, with a few stops n the way to admire the landscape. We both have Pinnacle road bikes. I've just got one big problem which could maybe be easily solved with advice from anyone on this forum. Basically, i don't know how the best way to transport our luggage would be. I plan to pack minimal, but i will still need to pack quite a lot of things with me. My first idea was to send an ordinary piece of luggage through a courier service, but it seems really expensive and complicated as you have to value what your sending etc. Another option i considered was to take my luggage with me on my bike by installing a rack on the back and getting some panniers to put on top and on the sides, but from looking in shops and online i can't find any that would be of decent size. Would any of you have recommendations on other methods of transport or expand on any of the ideas I've come up with already? Any help would be extremely appreciated!!

-Vincent