Also keep an eye on the Monarch Aircraft Engineering website. They took on adult trainees last year and with the lack of man power at the moment could possibly take more on this year.
Basically guys like you that have worked in other engineering trades and want to retrain as aircraft engineers complete a two year course and at the end are qualified aircraft mechanics. You would have to study in your own time for a licence but at least it's a way into the industry with a decent company