With regard to brexit and VAT you should remember that one reason why the EU is not such a bad idea is that no matter where you go the VAT system is very similar. This is based on the principle that the EU VAT law is based on certain official directions. So if you made EU trades out of the UK you will find out that it is the same in Germany. All you basically need is the German VAT number. To receive this you do not even need a company in Germany. Certain tax offices are in charge of certain countries to issue the German tax number. With this tax number you (respectively your tax consultant) will apply for the German VAT ID number at the Central Tax Register of Germany.