On the language front, although I'm aware that german is particularly difficult at A level, I don't believe that there's much correlation between GCSE and A level results for languages in general.
Personally, I know many people who achieved A/A* at GCSE for french, german or spanish but did badly at AS/A2. Conversely, myself included, there are some people who have got B/C at GCSE but improved their grade at AS/A2.
Just something to bare in mind, that's all. Like someone said already, a language is a really useful A level to have, especially for a Teacher.