[vba616]

Presumably it was meant literally, but the term "charity shop collector" seems to have some other meanings as well which are interesting to me as a non-UKian speaker:

   - A provider of "a charity shop back-end as a service", which disposes of donations 
     received by charity shops.

     e.g. https://live.ctrgroup.co.uk/third-sector/textiles-collection/ 

   - A person who collects things purchased from charity shops.
     
     e.g. "Harding is an avid charity shop collector, especially of sad and neglected 
     ceramic animals".

[chrisjj]

Sorry. By 'charity shop' I meant a retail outlet operated by a charity. By 'collector' here I mean someone who collects monetary donations in such a shop.

[chrisjj]

PS Come to think of it, I have never seen a charity shop in any of the many countries I have visited outside UK. All the more remarkable given in the UK they are so frequent and often large.

[vba616]

I assumed it's more or less what they call a "thrift store" in the US.