After doing some DD about the silver market in UK, I found following.
Silver coin (Legal tender) = VAT exempt
Silver coin/bar (non legal tender) = VAT20%
Silver numismatic coin(collector's coin) = VAT5%
*VAT = value added tax, which is equivalent of US sales tax...
Also, in UK, Silver Britannia has a special privilege.
Britannia is CAPITAL GAIN EXEMPT, hence if you live in UK, it's a good idea to stack britannia so you are not liable of the capital gain tax when you sell your silver above $200/oz in near future.
Disclaimer: it's all iMo~