Cap 493
I think I found the answer
CAP 493 – Air Traffic Services gave me the answer. Section 3 Chapter 2.
Approach control will provide the services below depending upon the airspace within which the aircraft is operating:
Within Controlled Airspace – Radar Control Service
Outside controlled airspace – Procedural, Deconfliction, Traffic or Basic.
Whilst outside of the zone, you will receive either a Procedural, Deconfliction, Traffic or Basic service.
[FONT='Calibri','sans-serif']On entering the zone – you are then under RADAR control and as such will receive all of the services defined whilst under Approach Control. These are: Approach Control service, Basic service and an alerting service. It also includes traffic information for aerodromes operating in classes C, D and E [/FONT]