I love going to London. Always something happening and just a great city. Housing wise its probably going to be abit more expensive than Manchester but I am not sure the difference. Have a look for Facebook groups of Canadians in London. There are lots of one for Aussies and Kiwis so assume there would be Canadian ones. I know a few friends who found places to live and people to hang out with through such apps.
Most of the online flat listings are scams, beware! and never send money Western Union. My daughter didn’t lose money, but did end up spending 6 weeks in a women’s hostel in London before she found a group to rent a house. She had a job prior to arrival as she was able to transfer with her company so I cannot help any there. The flat my daughter thought she had … there were pix online of the council tax bill, utility bills, etc, but the building did not exist…it was 3 days before she was to leave that the scammer first insisted on Western Union to hold the apartment. Then the cell number was disconnected.
It is still difficult and expensive to find housing in central London. You might try airbnb, but be really careful and check everything twice.