Sure. Me too. And if I have an unusual/unexpected request, I usually prefix it with the callsign too.
"G-CD is Bravo"
"G-CD report Tango"
"Wilco Tango, G-CD"
...
"Er, Tower, G-CD, question?"
"G-CD go ahead"
"Do you know the status of thisandthis danger area by any chance?" (assuming the danger area is outside his control area, so I know he's going to have to look it up or phone somebody about it)
"Er, G-CD standby"
And of course, whether you can ask such questions and when to and not to abbreviate or omit callsigns also depends on the amount of traffic on the frequency, the mood of the ATC person and so forth. Good judgment is more important than strict adherence to CAP413. Although for the PPL exams stick to CAP413, obviously.