How easy is it to learn how to do this and do i need a stand?

I used to just tweak the spokes and spin the wheel on the bike, and never really worried about making it slighlty out of true vertically or dished as long as it was true side to side. That was before i had decent bikes with decent wheels though…

Or is a truing stand the kind of thing that you buy and then gathers dust in the garage?!

How much do shops charge for sorting a wheel out? Never had a problem with the 819's on the mtb just the road wheels is a bit out now.

A stand (or jig) makes it easier, but not really necessary for occasional use. If you're any good and you get a jig then you'll become best mates with lots of people and use it(probably) more often than is healthy.
Bring a bare wheel to our shop and it'll cost you about a tenner for a true as long as the rim's not thrashed.