We got a cute little cottage in the Cotswolds with my niece (she was about 18 mths at the time) and it was perfect. Had a swimming pool for her, could stay inside and play games and let her toddle around, we could go outside and she could run around and chase the ducks... She loved it.
We booked a great holiday cottage in Pickering. It's a cute little town with a steam train running to the coast. there's a public swimming pool a few minutes walk from we stayed, and lots of nice cafes in the town. there's a little play park too.
You can drive into York in about 40mins, Whitby/Scarborough in about 30 mins if you get good weather. Flamingoland theme park and zoo is about 15mins away.
Just that really - me and DH are looking to go away somewhere around March time (avoiding half-term and Easter!) with our DS who will be 18 months then. We were thinking the UK might be easier (less travel time etc.) though haven't completely ruled out abroad. I was thinking a city break for maybe 2-3 nights though obviously need to pick somewhere where there is enough to do to entertain DS! We recently had 2 nights in Chester which was lovely - took DS to the zoo, had a walk round the city, lunches out, etc. So we want something similar... I just cant think where???!