does this work in UK (£)

Technically, the sign-up form for this plugin currently supports only US-based merchants. However, if you sign up before setting up the plugin, you should be able to use a UK-based account(we have had this confirmed by a UK-based user of the plugin):

https://wordpress.org/support/topic/for-use-in-uk?replies=7

Hey there @lyonbeton

For future reference, you should create your own topic to get support, as it’s easy to get lost in responses on another person’s thread.

The short answer is yes, it should work, as long as you signup before setting up the plugin.