My German licenses were issued in 2012. They are "pre-EASA," to make up my own terminology.
If your German licenses were issued in 2012, you would need to extend the licenses, anyway. Through the extension process, you will be issued EASA-Part-FCL license. You will need a valid German or EASA medical to do that.
I'm afraid you will have to come to Germany and get an authorized examiner to get you through the extension process.
Can/Should I transfer the German paperwork to the UK so I can do all this in English?
NO, not at all. You could as well accomplish that in Germany using the English language.
PM me if you need any assistance in doing that. I'm based in Munich, Germany.
WP