Most handling companies recruit dispatchers internally, usually as summer secondments, with a few being kept on at the end of the season if the need arises. Occasionally they recruit externally, but again just summer contracts. Your best bet is to start on check-in or in the ramp, do lots of shadowing, then apply for dispatch. External staff taken on tend to have experience already. I'm talking about ramp dispatchers or TCO's rather than the US style dispatcher. Either way, airport experience would definitely be a help.