Lewis,
Whilst it is all true what is posted above, GA maintenance could be worth persueing, if only to use this as a vehicle (no pun intended) to getting involved in commercial aviation, where the better money can be earnt.
Having said that, don't be tempted to set your sight's too low. GA may be easier to get into but it is also worth considering some commercial airlines that may be interested in your skills. There are some that employ mechanics without any formal (aviation) qualifications to carry out the more routine tasks such as changing wheels and brakes or cabin interior maintenance. This can also be an 'in' into the industry. Once you have your foot in the door and show a good attitude, skill level and character, who knows where it will take you in time?
The money you could earn is much better in commercial airlines. I would imagine in the region of 25k for unlicenced mechanic + overtime on top. Wheels and brakes / trim would be less though.
Good luck!