What are your educational qualifications?
When retraining a lot also depends on what income you "need". Sometimes people can't go an retrain as they'd take a wage drop in between.
There are certain oil and gas qualification courses you can do from hom if you want to go down that route.
Depends how far you want to progress on the wage scale also as to what you choose to do. Say lorry driver might be a good job to get into but i guess theres quite a low salary cap.