There is plenty of advice circulating about keeping safe when you reopen your premises/offices/shop. Hopefully you are already keeping on top of latest advice, but here are a couple of useful references.
First – the official guidance from HSE about workplaces. Download it here.
Second – charity shop specific guidance. Most charity shops are likely to already be receiving this advice, but if you are a small retailer then you might be able to follow some of the advice given in here yourself. Download it here.