lisalisa... you definitely won't be banned. Dh (a long time ago now) got stopped for doing 90 mph in the fast lane of the M4 on his motorbike and getting in the way of a police car on its way to an emergency call. (Awful, I know). He got fined for the speeding and for either driving without due care and attention or dangerous driving or something (can't quite remember which) and still 'only' got 4 points and a small-ish fine.
Don't panic. Perhaps they forgot to include the letter bit that said you could pay the fine and avoid the prosecution? Good luck in sorting it out.
Oh, yes, and don't say that you haven't seen your licence for ages. Just say that you lost it recently when your handbag got accidentally dropped into a lake (or something ) and you are in the process of renewing it (and then really do renew it!). It won't have expired. They don't expire till you're 70!
Good luck in sorting it out.