Kubla, I don't think there are any x country centers in SE MA. You could try the Weston Ski Track, which would be the closest for you, for a private lesson. It's not that pretty (a golf course overlooking the highway), but it's good for learning. It's right near the intersection of 128 and the Pike. Great Brook Farm in Carlisle would be prettier, but further away. They have lessons, too.
I think you will find that this is a sport that is done by many older people. You can ski at any speed you want and find terrain that suits your needs. I skied for about 12 years on beginner trails, until 1) I got better skis with metal edges and 2) I found friends that were willing to coax me up and down the hills. It didn't take me very long to "get" it. Of course, taking up cycling in the interim helped more than anything else.