Hi Ellie, welcome to the site.
Bedlington seems to hit your requirements in terms of green spaces and commuting. In terms of demographics it's a fairly even split from what I can tell between families, young professionals and elderly.
For groceries there are now 3 supermarkets (Morrisions, Lidl and an Aldi opening imminently) as well an independent discount retailer at the top of the street. For other shopping there are some specialist independent retailers on front street but you're not going to get the same mix of national chains you get on other high streets. There's a well established music shop, cobblers, butcher, home furnishings, travel agent, cake shops, plenty of hair dressers, nail shops and dog groomers etc but you will likely need to travel elsewhere for clothes and white goods etc. There's a few coffee shops and I'm currently setting up a coworking space on Front Street.
There are community groups that host events at the Community Centre and Salvation Army covering lots of topics like crafting, history, running, fitness.
I have lived in Bedlington most of my life apart from a few years overseas. It has its problems the same as anywhere and generally there can be a feeling of apathy and that the town is overlooked in many respects but if you can see past that there are definitely things happening if you get involved.