I'm hoping you all can help me get some direction...

I started riding a few months ago, but have been off the bike for the last three weeks due to a muscle injury. Now, I'm feeling better, but my riding backslid a little. Before my break, I was averaging about 12.5-13 in the hills and around 14 or so on flats- I've slowed down slightly. I've ridden up to 50 miles on both hills and flats, but am riding shorter distances since my time off. My goal is to increase my speed a couple mph and to work up to a century in feb.

I just got a trainer and a spinerval dvd (just the 1.0 to see if I like it at all). I also have access to a couple of spin classes, but have a difficult time getting there. I only really get out to ride on weekends. My boyfriend is working with the Cyclist's Training Bible- and is very excited to have a "plan". So far, I've just tried to ride and keep it fun. Now I'm thinking I might get to my goal faster if I try to get some direction.

I'm not looking to race, I just want to increase my speed and distance. I enjoy riding on hills more than flats. I was thinking two or three times on the trainer doing spinervals or interval training out of the book and then a short hilly ride and a long hilly ride on the weekend. I might throw in a spin class here and there. I assume I'll change it up a little every now and then.

Do you think this should get me where I want to be? Would you suggest something different (or specific intervals to increase speed)? Do you think I would be better off sticking more "religiously" to the Cyclist's Bible (it seems a little structured and race focused). Is there another Spinervals tape that really helped you with speed? Anything else you would suggest?

Any advice or opinions will be greatly appreciated!! Thanks in advance!