Just go into the money changers with enough cash and say that you want to transfer X amount of pounds to a UK account. You may be able to negotiate a better exchange rate than that shown on the board but that depends on the amount being transferred.
Give them the UK bank's name, address, sort code and the account number and name.
They will tell you how much you pay and give you a slip showing the transfer details and exchange rate.
The rate will be better than that offered by the banks.
I regularly used the Al-Saad exchange on Al-Saad Street and the money arrived in the UK within hours.