Sandy Beaches in France

aeronic

Ok, so this is a wide-ranging topic, apologies in advance.

We love the beaches in devon, but the weather last year was quite poor for 2 out of the 3 weeks we spent there, so wanting to look further south for a better spot of weather - but not too hot, nor too far as we are starting in Yorkshire.

We are both teachers, so will use the summer holidays, and have a 2.5year old who loves digging on the beach. 

Which areas of france would be best to look further at and research in more depth?