Stuart, you can scratch build your trainer. For the first one, I would recomend a set of plans. If you can locate some back issues of RC Model World, a UK publication, each issue has a free plan. Most are electrics and most all have good instructions in the article. The magazine is also the best of the modeling magazines I've seen. It has a broad range in information. The reason I recomend a magazine over a book is the magazines are current. I purchased some books a couple years back, and I was disapointed in the content as it was really dated.

There is also a great deal of good information here on RCUniverse. http://www.rcuniverse.com/university/ would be a good starting point.

I admire your desire to build. Nothing like seeing something you cut and glued together taking air for the first time.

Don