Difficult choice. If you can afford to do your CPL/IR/MCC you might aswell do it as soon as possible as either way you are gonna have to do it. Your problem then is your lack of hours so you could do the FI course and instruct while you are looking for another job. To get to your thousand hours by instructing will take you well over a year, thats if you do it full time. Everyone knows that FI`s aren`t the best paid aviators so that is something you will have to bear in mind. I think that getting an airline job with only 300hrs is gonna be quite hard at the moment but you never know.
My advice: give instructing a go, you might like it, you will build hours and it will eventually lead to other things.