Here y'go...
xxx radio - air/ground
xxx information - AFISO
xxx ground - ground movements controller (usually only at busier airports)
xxx tower - aerodrome control, ATC, in the visual control room
xxx approach - procedural approach control, ie non-radar (civil), approach radar (mil)
xxx radar - approach radar
xxx control - en-route centre (unlikely to use this unless you're airways/crossing airways traffic)
Remember, when we hear you call, we have to grab a fresh flight progress strip (the things we write everything n - one for each a/c) and start writing your details as you're speaking. We may be very busy, and using more than one freq, so
1. Select freq, then listen for a mo for a suitable point at which to call.
2. Make initial call brief, ie "xxx radar, G-BLAH"
3. You will get back "G-BLAH, xxx radar, pass your message
4. Go back with "xxx radar, G-BLAH is a xxx from EGaa to EGbb (airfield names are fine) maintaining xxx ft on 10xxmb, position, request (type of service)"
We don't need to know if you're u/t, solo navex, low hours etc, though we can often tell from the sound of your voice. Do tell us, however, as soon as you think you might be experiencing ANY sort of difficulty. We have all sorts of tricks up our sleeves to help extricate you from mire, and we probably won't laugh. Why only probably? If you want a definite, bring doughnuts on your visit!!!