If anyone is purchasing gold with value which is over the limit Level 1 set by each EU country differently, seller has to make a KYC due dilligence about identity of buyer. The most of EU countries has limits between 1000 and 3000 Eur. If your purchase over Level 2, what is 15,000 Eur for all Eu coutries, seller has to make KYC due dilligence also for source of funds. All documents from Dues dilligence has to be stored for at least 10 years from the 1st january of the next year after the year of purchase.
So there is no way how to buy gold anonymously in EU.
Seller does not report anything. Or to be absoluteluy honest, seller does not report anything unless he does not consider transaction to be used for money laundering or financing terorism. If seller consider transaction to be too risky based on las against money laundering and financing of terorism, there is legal responsibility to inform Financial unit of Police of country where seller resides.
https://silvergoldbull.co.uk/
This people will buy BTC and give you gold bullions . . .
High limits , in most case not need to show ID , if need show ID is just for there record only they not share to 3rd-party etc TAX agency etc.
So best bet is to visit them in person in UK do the trade then fly home with the gold . . , Win/Win.