timing belt is a doddle, just take your time and it'll all go back peachy.
I invested in a set of lockign tools from difflock, they were 70 quid at the time but seem to have gone up in price. I'll be doing other mates belts so was worth the cash and makes the job v easy, and difficult to get wrong.
As for servicing, it depens which servcie you are doing, for a 6k service you'll need, oil(part or fully synthetic), oil filter, fuel filter, air filter, a sump plug washer, odds and sods of grease and lubricant for parts round the car. Might also want to change the rocker cover gasket and half moons.
for a more major service you'll be needing swivel hub grease, gearbox oil, tansfer box and diff oil
I've not found any job too difficult on the disco, apart form trying to get the viscous coupling off with out the correct spanner. Do yourself a favour and spend a fiver on one, makes life a whole lot easier