I used to throw bags on during my uni holidays at LHR for EI and then BD......
As soon as you have some initial Airport exp. you can move thru pax services to dispatch and or any other dept that is recruitng. Handling agents offer more openings but mainly due to the turnover of staff. If you want to stay in the industry try to get in with an airline Good luck, You'll need it! But when you get something you enjoy you know your hard work will have paid off!
WTD