I'm sure money is not what Morrigan was talking about... convoy guys do not earn a fortune and I've seen some jobs in the UK- regular, low drag, low risk- that are paid a lot better. With convoys- I used to work convoys as well, so I know what fun(?) they can be- the risk far outweighs the reward. They are a good starting point if you want to break into the PSD market, you'll get opportunities to network.
But, on a day to day basis consider the following points; if you're lucky you eat dust all day- possibly 16 hours plus; if you're unlucky you get contacts. The worst case I've seen are the fuel convoys in the early days, slow and very explosive targets!
I am not trying to put you off, but convoys are unlike anything else you'll have seen or done. As Morrigan suggested get a HECPO course done- including live firing- and I would suggest looking at Afghanistan as a start- check out EODT, Hart Group, Compass( they were recruiting recently, a recruit on a regular basis) and Armorgroup.
All in all though convoys can be great, or they can be shit- it depends on how lucky-or good- you are.