I tend to clay about 3 times a year, a good thorough wash, dry, clay (with a heavier cut if not done regular) or a lighter cut if done more often, the a good polish and a layer of wax or two.

can recommend these people

http://www.cleanyourcar.co.uk/

and this product
http://www.cleanyourcar.co.uk/zaino/.../prod_477.html

although the meg's claying kit is good, you may find that its to mild for your car if its not been done in a long time.

Also this
http://www.cleanyourcar.co.uk/detail.../prod_225.html

acts as a really good clay lubricant when diluted and can be used to clean the car of dust, really good when used in a spray bottle.