Good luck!
Where are you? There may be some local casual / social rides / groups, and that makes it a great way to meet people, and it always seems easier to ride further and faster with others.
The most important thing about any exercise regime, whether in the gym or on the bike, is to make sure you have FUN.
That way, even if the weight doesn't come off as fast as you'd like, you're still having a good time.