Dear @Ant,
Thank you for sharing your question with the Wefugee Community!
Unfortunately, I am not an expert on tax law/regulations. However, I found a thread on this platform, which might be useful to get some general information about tax return etc.
I can also recommend to seek advice in a so-called "Lohnsteuerhilfeverein", which is basically an association, which is specialized in supporting people with their tax claims. There are thousands of branches and offices in Germany and I am sure there will be one close to your address also (you may want to search on this website).
Otherwise I hope that somebody else in the community can give further information or share experiences.
All the best,
Meike