This is an accepted solution.
This is Max from the Shopify Team, again. I just replied to your earlier post, but will share some more info here as well (just in case).
Shopify Payments is one payment provider that we offer (it's our own solution). It has its own set of requirements to use it based on what you sell and where you are. At this time, Shopify Payments users in the UK are required to sell in GBP. More about those requirements here.
There are other available payment options for your location. The options for the UK are all listed in your admin under Settings > Payment providers or you can review them here.
If you decide to change your currency, this can be done by messaging our support team directly. We'd also be happy to take a closer look at your account, if needed.