Gee it's got complicated since I left almost 20 years ago. A quick letter to CAA. Nice man from CAA wrote back saying I needed Type Tech exam, Air Law, Loading and VP Props (never did understand why I needed the last 2), an I/R (kindly arranged on one of HM aeroplanes with CAAFU examiner jumpseating) and an 1179 - again on one of HM aeroplanes with QFI mate given one off approval to conduct the 'test.'
Then it was just a case of writing the cheque and checking the post every morning for the next 10 days for a green book in a brown envelope.
And then I spent 2 years trying to get my first job with an airline - but thats another story!