Generally, there are three routes:
1.Forces Training
2.Airline or Maintenance Company Training (apprentice)
3.Ab-Initio (college training from scratch)
Although ex-Forces myself, I would go for an apprenticeship these days given the choice. The advantage you will have over the Ab-Initio route is that you’ll earn wages throughout training and get far more of the all-important hands-on experience (with the prospect of a job when you finish)
You’ll get plenty of comments from Maintenance Engineers, trying to steer you in other directions!
However, its a varied and challenging career and if you put the work in and get Licensed, you will have qualifications that will generally be in demand
Hope this helps