15 mins out and they will want ETA and if you require fuel or not. On that freq you will get swamped by every high level CAT traffic out there with the same handler in multiple airports.
Don't worry about it.
Use "G-xxxx, Handler callsign, including airport" eg "G-ABCD, Speedy Brum", Which translates to "G-ABCD, Speedbird Birmingham"
When they eventually answer after getting stepped on a few times.
"Speedy Brum, estimating at minute xx request avgas fuel on arrival G-ABCD" or for that matter "negative fuel".
I use speedy brum because there will be zero chance you will used them as a handler but it does show that the handling frequency's are quite a bit more or can be more informal than ATC ones.
The reply will probably be "roger see you on the ground G-xxxx"
You will hear loads of other calls to different airports with a load of stuff you will have never heard of before which will be data for the load sheets for the next sector and any service requirements. It won't be as correct RT as your used to on ATC don't worry about it.