Welcome aboard cheffy, I re-started cycling a year or so ago to help with a simplistic 'eat less, move more' self help programme.
It works, but it's seductive!
You can end up setting yourself goals and achieving them, and then setting higher goals and so on. I've found that the good thing about this is that because it's enjoyable I stick with it. I haven't done any monster rides yet, and haven't got any plans to, although I keep thinking about getting myself fit enough to do an Audax in the New Year. Whatever you do, enjoy your bike and enjoy the riding!