Hey,
Someone asks a similar question a few days ago, this link should give all the info you need to get going
http://www.oople.com/forums/showthread.php?t=81724
If your budget is £100 then you would best going for the cheaper kit and getting plenty of paint to practice with.
Createx paint is cheap and water based and I would recommend using that. I personally would say get a decent paint mask and would also recommend spraying in a well ventilated area. I mostly spray out in the garden so, but it can get a bit chilly
.
Anyway hope that helps and any more questions ask away.