If it's a full service, you'll be looking at:
Oil change including sump bung washer change,
Oil filter,
Spark plugs,
Air filter,
Fuel filter,
Coolant check,
P/S fluid check,
Washer bottle re-fill,
Plus they should also do a C/O mixture check, making sure your not burning too much or too little fuel.
They should also do a general good look around the car checking the important bits like tyre wear, brake pad wear, suspension points, exhaust security, front and rear wheel bearings etc etc.
If the garage is any good they'll give you list of any potential problems, but they won't just crack on with the job as they'll need your approval.
If you don't know the cambelts history then it's a good idea to get it done anyway, book time for a cambelt change on a 16v is 1.10 hrs, so don't get ripped off for it.
And let them know the plugs are relatively new, and they may not need to change them.
Hope this is of some help.
Lewy