Your probably too late for a job at glasgow this summer.
Next summer drop your cv into the ground handling agents.
If you really want a job in the airpoirt then you can do a college course at James Watt college at either Greenock or Kilwinning campus that will guarantee you an interview with servisair, although this is primarily a route to a check in job. Think it costs £200.
I applied for a check in job 2 years ago, however went straight to dispatch and have since gained a TRC/TCO license for British Airways & Virgin Atlantic, ill soon be getting involved with Emirates and im also a dispatch supervisor aswell so dont be put off applying for check in jobs.
You could also apply for a baggage handlers job, however IMO, dispatch is the best job you can do in a GFHA, however you are paid better wages as a baggage handler.
Any time ive seen a handling agent post a vacancy its been on the job centre website. The advert I applied from was in a paper. Ive never seen them advertise on any other websites.