I actually agree with our esteemed 'ATCO Two'.
Remain outside CAS, that means laterally AND vertically, and squawk A7000 with ALT if possible.
No need to call but if you really, really need a 'hand' to hold when close to the LC CTR then call, keeping transmissions to a minimum. LTCC frequencies are not the places to 'practise RTF'. Remember, even if the RT does not appear busy that the controller is likely to be busy on other channels. For instance, a considerable amount of communication takes place on landlines, and air transport flights will operate in the area of responsibility without actually calling on the RT. Please also remember that Thames Radar is not a LARS unit and is not thus equipped. The availability of Thames Radar is specified in the UK AIP under entries for London City and Biggin Hill airports. The adjacent LARS units are Southend and Farnborough. Flights outside CAS which plan to pass close to the Biggin Hill ATZ and the 21 IAPs should, in the interests of good airmanship, contact Biggin Approach in the first instance for FIS.