You're right, the 8v is a chain engine. It won't need changing. If it rattles, it can be tightened quite easily, but you have to do it right. It'd take about 15mins to do yourself. If it needs done, I'll post instructions.
Get the oil changed and make sure it's 10/40W. Don't use thinner oil than that.
The plugs can be bought from EBspares for about £20 for the 8. They are the OE 4 electrode Golden Lodge plugs and the engine seems to prefer these to any other plug.
Front wishbones and drop links may need changed. Wandering under heavy braking or when travelling at high speed could suggest these are to blame. Sometimes you might hear a rattling or clunking aswell. The drop links will cause a clunking as these attach the anti-roll bar to the wishbones.
Drop links are about £10 each and the wishbones can be found for about £30 each from motor factors. I got some from Alfashop for £35 each last year.