What Hora said.
Fork shouldn't need more than a lowers service, if it needs more then seals are easy enough DIY, bushings should be OK, if not the fork might be salvageable as long as the stanchions aren't worn, but its a job for the pro's (£120ish at TFtuned or the like).
Shock, should be serviced anually profesionaly (£100) for longest life/best performance, but it'll (probably) be rideable for years without. You should give it an air can service every so often though (see the internet for guides).
Shock eyelet bushings, hold the back of the seat and lift the bike up and down gently, any play/knocking is most likely worn shock bushes, ~£25 DIY repair (cheeper the next time once youve got the bits), see the net for guidees.
Frame bearings, take the rear wheel and shock out and put the bike in a stand, feel for any stickyness or play in the suspension, if there is any then its an £80-£100 job at the LBS unless you've a blind bearing puller the right size. DIY the bearings are about £40 (get good reputable ones), and a bearing puller £60+.
Everything else, the park tools website has guides.