Hi, You will be able to login without issues on the UK site, but I am not sure if you will be able to create a store on UK. Can you please try and let us know? Also make sure that you have linked your Paypal sandbox account with your sandbox user, If you are not able to do it, please provide us the paypal sandbox account and we will link it for you. I would still suggest that you create a new Sandbox US user to create a store on US site. Cheers!!!
No way - I wasn't able to log into UK site; moreover I was not able to create a new user, your system does not explain what's wrong: very primitive test user creation form without showing which stipulation for a new test user was incorrect. Waste of time.