Hello Zanek, I am Keith, one of the experts on Just Answer, and pleased to be able you help you with your question.
The branch office in Germany would appear the easiest solution. It could be registered for the German equivalent of VAT. UK VAT would not be involved.
Any profits made by the German branch could be aggregated with the parent organisation and normal UK taxation applied to the integrated incomes and expenditures. The UK has a double Taxation Convention with Germany which precludes the same income stream being taxed in both jurisdictions. This is achieved by means of tax credits, the tax paid in one country being allowed as a tax credit against the liability in another. The Convention does not protect from differences in rates of tax, however.
I do hope that you find my reply of assistance.