Thanks for your help guys. I'll give them some consideration.
I should have done this before asking ... Looking on the net, Lightworks seems to come highly recommended - http://www.lwks.com/ The free version has all the features of the paid version but only exports to 720p (instead of 1080p). However, that will suffice. I'll probably give that a go first, and have your other suggestions as back-up in case Lightworks is too complex for me. (Weezy, no need to do any more searching this evening )