I have a US Uber account which I have yet to use. I'll be in London next week and just received a 15GBP Uber credit from National Express which I would like to use to get from Victoria to my hotel. My question is my Uber account is linked to my US cell phone. Will I have to use that # to request a car or will I be able to switch to and use my UK sim?

Really not sure of how any of this works