It is often hard when developing a new area to get community facilities up and running effectively so that people can use them from the start and don't get into 'bad habits' of going outside the area. Have you asked those involved in similar developments (eg Orchard Park) what lessons they learned?
A key community facility would be a building - either set aside or shared - for a local church. Unlike clubs etc, a church exists for its non-members, actively seeking to involve people of all ages, nationalities and backgrounds. It is cheap too, as it is self-funded.
Cambridge attracts lots of Christians; many churches in the city have seen significant growth in recent years. Help newcomers to the city get out of their cars on Sundays by planning for a local church.
This would require a building with 1 big space plus breakout rooms for children's work, cupboards for storage & an office space. Churches often run events throughout the week for all sorts of people (eg toddler groups, youth groups, 60+ groups), but the building could also be shared with scouts, money advice centres, drop-in baby weighing etc etc.