everyone from Europe is European, you have to hail from some country in Europe, its not really that simple to say I'm European and not British as your passport will say otherwise
and if you no really no longer want to be British then you will have to move elsewhere apply for residency, live there for the requisite number of years required and then apply for that country's passport
British people have never been required by economics to move outside their home country except by choice and they really come across as spoilt brats at times
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'put a bit of lippy on and run a brush through your hair, we are alcoholics, not savages'