Personally I would go for it, after all what have you to lose? You could always pick up one of the many Airframe books available such as the FAA A and P ones and swot up on it a bit before you go for your interview...... but the location and the shortage of Engineers I think you may be in with a good chance....... I myself started out as a Ex RAF Engine Techy and was taken on by a company culminating in me getting both of my Airframe Engine licences after a lot of self learning........ remember you aint going to be doing a lot of if any sheetmetal work, so a lot of the job will be removing components etc...... which is similar in both engine and airframe work..