Do it, do it, do it!
There is a growing community of adult ballet students, and in some cities , a really good provision of classes. In my small regional town I get 2 to 3 well-taught classes each week. I've always danced, but lots of people start in their 20s.
Without outing yourself, are you able to get to central London, or central Manchester, or Bristol, Newcastle, or Leeds, or Oxford. I can suggest really good professionally taught classes in proper studios in all those places - and others (avoiding the Dolly Dinkle schools in church halls).
To get more information about adult ballet classes in the UK, have a look at this messageboard:
www.balletcoforum.com/forum/9-doing-dance/
Lots of us adult ballet students there just avoid the endless egotistical thread called "Simply Adult Ballet" it's mostly just about one slightly delusional adult student
A more US based site, but with excellent advice, is here, called "Ballet Talk for Dancers"
dancers.invisionzone.com/
Don't bother with these new-fangled "Barre" classes. They're not ballet - a waste of your time & money if you want to learn actual ballet.
Learning ballet will feel hard for the first few weeks, but if you take it slowly, enjoy the beautiful music, and really listen to your teacher's corrections, you'll gradually get a feel for it. A good teacher should be giving hands on corrections & guidance, but not roughly. They shouldn't require you to have your feet in 180 degree turnout, and they should never encourage you to wear pointe shoes until you've done about 3 years of consistent classes.
A good teacher should correct you - and you shouldn't take it personally - they'll tell you what you're doing wrong so you learn to do it correctly. In fact, I consider I've really bombed a class if I don't get a correction - it means the teacher hasn't been looking at me! I go to pieces if I get praised ...
Anyway, you don't need any special equipment - just wear form-fitting clothes - leggings and a close fitting tshirt or best top. You can wear socks instead of ballet shoes at the start (in fact I prefer to do the barre in socks as I can feel the floor better). And canvas ballet shoes only cost between £10-£15 from an online dance sgop such as Dance Direct.
To be honest, you really won't look like Darcey Bussell, probably ever. But you will learn to do amazing stuff with your body (like pirouettes across the floor), move gracefully, get aligned & supple, and move to beautiful music. And meet other lovely dancers - we're all a bit besotted with the art ...