Somewhere to stay about 300km south of St Malo

At the beginning of April we are heading up to St Malo to get the overnight ferry to Portsmouth. The journey is over 600kms and we’ve learnt that is too much for us in one day, so we propose splitting the journey.
On the outward journey I’ve booked us into a fairly functional hotel near Niort, not far from the motorway. Coming back, we can be more leisurely and I wondered if anyone has a recommendation for a hotel, good restaurant, both ok with dogs. Does not have to be Niort, but should ideally be about 300-350kms from St Malo.
Thanks.