I had a few german colleagues and it was a pain in the ass and some of them where not able to do it in the end. Problem is that the LBA is not able/willing to release your medical records and therefore the caa will not accept your application. Doing an initial is not possible because you can only do that once. Basically you are screwed! It is really a big problem. What you can ask the caa is if they are happy if you can provide them with all the data but then you need to call every AME you have EVER been to. Then ask them to provide you with all your data and forward it the caa. Another option might be to change it to an irish or any other easa licence and try to get a uk one.
Best of luck you going to need it!