I'll be in London for approx. 7 days in mid-October, and want to rent a smartphone with a UK telephone number. I'll be looking at flats in unfamiliar parts of the city, and want to be able to easily use Google Maps and communicate with lettings agents. My U.S. smartphone is locked and won't work with a SIM card.
Are there any options for renting a smartphone beforehand (I'm in the San Francisco Bay Area), or from Heathrow or somewhere in the London city center? Thank you in advance for any advice!