Getting my bike serviced

[The Stranger:Me]

Just go from the mileage - Go forward from here && now. Although you can also play "catchup" if you suspect a major service or item has been missed

But on a limited budget do only what you have to - If it ain't broke, it dont need fixing

In general I got to agree, but unless he has receipts or a service record (which he doesn't) it doesn't hurt to put it in a known good state.
Valve clearances can be fairly important and are usually called for in the 20 or 24k km service, if they were done on time they are probably within spec and the cost will be small, if not it may save him some money in the long run. Not only that but if he's not sure on suspension, steering head, sprockets and brakes, well waiting until they are broke can ruin your day - or kill you. Personally I tend to favour fixing prior to broke.

[Max Preload]

I figure that as I have no idea whether previous owners have kept up with it, I can't really tell what point of the schedule I am at. Which sort of leaves me thinking like it'll be the 'all over' that's required (sigh - there goes the luggage I was hoping to buy ).

You've got a bike of unknown history so, yes, you'll need to work through what needs doing - start with the important stuff - brakes & engine. For most maintenance you should be able to do it yourself - I'm sure you can find some friendly local KBer who can show you the basics. It's going to be an ongoing expensive hobby unless you can do most of it yourself. Besides, doing it yourself is half the enjoyment.