Child friendly activity in CAmbridge - any suggestions?

[Cll]

going to a 39th Birthday party at The Felix Hotel in CAmbridge on Sat night and spending the sat and sun there with kids aged 2 and a half and 5. My recollection of Cambridge is that its freezing even on a mild day so wondered if anyone knew of any indoor play centres/ballparks, kiddie friendly museums or places of interest - or even outdoor activities on the off chance it isn't below zero.

All suggestions welcome

If you have your car with you Duxford is well worth a visit, cll. It's just south of Cambridge off the M11.
Also in that direction is Wimpole Hall and Home Farm, which might be having one of its lambing weekends.
I know these are both partly outdoors but you might be lucky

thanks

There is also the sedgwick museum which has a dinosaur skeleton, punting - you can even get little lifejackets, there are plenty of outdoor play areas, the botantical gardens, Wimpole hall is great and also (although I have never been) there is a zoo at Linton (10 miles out of Cambridge) and Shepreth Wildlife Park, parkside pool as a toddler pool, Planet Zoom at Ely has bowling and an indoor play area and the The Red Lion pub in Grantchester has an indoor play area too.