As Fazed says 24 K miles is the big service.
What sort of history is with the bike, what has been done previously?
The manual tells you what to do, but.
If it was my bike and the previous owner couldn't provide any information, I would be changing the fork oil, brake fluid, coolant, clean or replace air filter, change spark plugs, change oil and filter, go through and clean all electrical connections, check and grease all the swinging arm and suspension bushes and bearing, check all the wheel bearings, clean all the calipers and brake pads, lubricate all control cables, strip, clean and lubricate the EXUP valve and check the valve clearances. Once that is all finished run the bike and balance the carbs, £500 - £600 easily at a dealers (who won't do half of it). There are smaller independent service places or guys working from home, go on advice from previous users.
You might find the rear shock is well past its best £80-£150 will see it rebuilt by a specialist
If your bike is off road for the winter, get a manual (Haynes is better than the Yam one if you are not a trained mechanic) and work your way through the jobs on evenings and weekends. You will learn loads about your bike and have the satisfaction of doing it yourself.
Oh BTW checking the valves is easy, pulling the cams to change the shims is not for the faint hearted.
Good luck