You need to be at least an EU resident to open an account with any UK bank nowadays. They will not open accounts for non-residents unless you go through a dedicated international banking team, which may not exist with all banks.
Something like Revolut or Transferwise borderless may be useful.
Is Revolut launched yet? I wonder if I can gain access and use it in Europe next week?
I have a HSBC Advance account. Will that help me open a basic free HSBC account in the UK?