Welcome to the area! I work in Malden, live in Stow (37 miles west), and teach riding in Lunenburg, so I spend a lot of time on the 2-2A corridor. Your best bet is going to be west - Concord, Acton, Bedford, Westford(stay away from driving on 128)…if you can get on the road in the morning or before 4, all of these areas will take less than 30 minutes; for an hour commute, you can get out to the 495 ring. The barns mentioned in Concord are a reasonable drive and have lesson programs…there’s also Churchill Stables in Bedford and Eleazer Davis Farm (though I don’t know if they have school horses), Volo in Westford with a big lesson program, Fair Harbour in Acton (good trainers, not sure about lesson horse options), Red Acre Farm in Stow (the Steegs)…further out is Orchard Hill in Berlin. Liberty Tree Farm in Acton is actually walking distance from the commuter rail station, but I don’t know what their lesson options are. If you are just looking for rides, post on the Equinesite Massachusetts horse scene BB…lots of people can use help getting riding done (especially if you can come out during the day!)
Chestnuthunter, if you are looking for reasonable board, I would suggest looking for a small private farm…the Equinesite bb has a decent classifieds section and you can check the books/boards at Dover, Smartpak, and Pegasus Farm Tack. Anything with an indoor is going to be close to $1000…if you can come further out to central Mass, prices go down quite a bit.
Feel free to pm me for specific info on any of the farms in the area - if I know anything, I’m happy to share.