Stripe are telling me that I have to charge in GBP because I have a UK bank account. But given that I am mostly marketing to a US market and Americans (as a huge generalisation) seem to find it difficult to handle currencies other then USD, this is going to put people off my courses. Is there an alternative? It seems virtually impossible for me to open a US bank account.
According to Stripe's list of supported currencies for each country, UK customers can charge in USD.
(If you did want to open a US bank account then Stripe do offer that service with Stripe Atlas, but I don't think that will be necessary.)
I'd just go ahead and sign up for a Stripe account. Once you've done that, you should see the option to set your currency to USD from the Integrations page of your Thinkific admin dashboard.
Please let us know how you get on!