Hi there @Elledon2020!
Don here from Shopify. :)
It is indeed the case that we cannot support businesses selling hair on Shopify Payments UK.
You can check this out in the 'B. Getting a Service Account' section of our Terms of Service for Shopify Payments UK under 'Products or services that are otherwise prohibited by our financial partners'.
I would reach out to those services if I were you to see how they can accommodate your business needs and what you might need to do to get set up with them.
All the best!