Retire then work part-time

Just pop in have a cofffee & general chat dropping the topic into the conversation.

I would talk face to face to make general enquiries, and then follow up with a letter or email. Be guided by their initial response.
There may be opportunities for pre Christmas work, this may lead to a more permanent position.
Good luck x

I would ask them directly. (When we retired and moved to the seaside there was a lovely bookshop I would have loved to have worked in. Closed down before I had a chance to ask!)

I think you could approach them face to face.

As you walk around urban areas, shops sometimes have notices in the window saying they have a vacancy. Have a look - you might see something else you fancy.

Go for it! They may not be able to pay very much, but if it is a nice place to work, that may be enough.
In the summer I offered to work in Waitrose for free, just for the opportunity to stand near the chiller cabinets

Personally I would call in when it is quiet and have a chat and casually mention that if they are looking for any extra staff or maybe have some vacancies coming up.