We stayed here last September and I would really recommend both the company we booked through and the gite itself:
http://www.holidaytots.co.uk/toddler-an ... y-107.html
(Let me know if the link doesn't work)
The lady who runs Holiday Tots was really helpful and attentive and the gite itself was perfect for us. It is set in beautiful countryside but not too far from St Malo (there is barely any traffic on the roads out there so the journey was quick and pleasant). The gite is owned by a British couple (who coincidentally lived in SW London before they moved out there). They were also really helpful (they live in the adjoining house (or at least that was the set up when we stayed there)) but struck up the right balance of being attentive whilst giving us our privacy. We stayed there with our then nearly two year old and I was also pregnant at the time.
Let me know if you want to know anything else.