Woodlands
Great campsite - make your own entertainment at night as there is no clubhouse (take the BBQ)and no pool only a toddlers paddling pool in the park.
That is the worst over (depending on your view on entertainment)
Location is good for Torbay, Dartmouth etc.
Try taking the ferry / steamrail link to Paignton from Dartmouth.
The park is excellent with loads to do in the wet and dry, you will not be disappointed - I should go now as your older girl might grow out of it in the next few years, I would say ideal kids ages would be 4-16YO.
Best bits for us - water rides, tobbogan rides, birds of prey display, animal farm and indoor play area (huge).
We went there a lot a couple of years ago and now try to go one weekend a year.
One other thing for anyone looking for storage in the area - Woodlands are cheap and secure.