I’m just about to finish my radar training so have just had it all drilled into me about what each service means. Basically you have 3 services outside controlled airspace:
Basic service: you get weather information and any other information that may help your flight for example if it is known that your destination is closed you will be told, you can get general traffic information something like “there is a lot of traffic to the south of Brize” something like that.
Traffic service: we identify you with a squawk or turn or some other method so I know which blip on the screen is you, I tell you where any conflicting traffic is and any information you would also get with a basic service but the traffic information is more specific to you such as, traffic 12 o’clock 10 miles right to left indicating FL50 etc. all you need then is to let ATC know when you are climbing or descending or turning so we know if that will take you into conflict with any other traffic but you are responsible for not hitting anyone
Deconfliction service: Again we identify you and you shouldn’t climb descend or turn without telling us 1st it’s the same as a traffic service but when we pass you information on traffic we give you a heading or climb or decent to keep you away from it for example G-XX traffic 2 o’clock 12 miles right to left if not sighted turn right heading XXX, you should not really ask for this if you are VFR as the deconfliction advice may take you into IMC but if you let ATC know you must stay VFR they will try to keep you VMC
As for R/T just learn what info we need like, callsign departure and destination aerodrome, ac type and how to ask for the service.
PS FIS doesnt exist anymore thats the basic service now
Hope it helps