Servicing is divided in 3 main categories, alternated this way, every 9000 miles or 1 year, whichever comes first: P1 P2 P1 P3 P1 etc.
P1 (not much more than an oil change) cost varies in different parts of the Country NW for example is ~ ?100 supplying your own oil.
P2 intermediate service, aim to pay in the NW ~?115 if you supply your own oil
P3 Major service, the most expensive of the cycle. Aim to pay ?250/?300
As a rule, always ring all dealers in your area and play them against each other to get the best price!