Training on a trainer can work great! I'm doing a lot of it lately (I use Spinervals, but which DVD's or whether to just watch movies is a hot topic - you can search the forums for more details). Actually this article just hit my twitter feed today. You can definitely get in a great workout! You do have to start working on longer weekend rides, but for now it can be good to build base.

I hope others will chime in too - but it sounds like a great goal!