Dear @Ruhr,
Welcome back to the Wefugees Community and thank you for reaching out to us again. As long as you left Germany voluntarily (not deported), there should not be a re-entry ban - I would agree with the information you received by the embassy. Furthermore, I don't believe it is relevant to explain the British authorities about your past in Germany when applying for a family reunification visa. Am I right, dear @mbeon-fardeen?
In any case, please don't hesitate to get back to us with any further questions.
All the best,
Meike