i am 14, and in the market for a cheap spotting scope too, but i don't think you'll get good photos from a full kit just costing £100. the camera adapters can cost £45+, and a bottom rung new spotting scope about £150 with eyepiece, and the bottom of the range ones seem quite prone to chromatic abberations, which sort of ruins photos.
even buying second hand, (which is quite reliable with spotting scopes, as they are more hard wearing than binoculars) i'm not sure you'd be pleased with the photos.
maybe the best option is to carry on saving? i'm sure you'd be much more pleased getting a better scope in 6 months then a cheaper one now where you may end up just wanting a better one
i'm currently doing alot of looking around and waiting till christmas to look at buying, as after trying a few in a good shop, it looks to me like its worth waiting