I wondered however is it possible to become a ppl instructor and move into simulator instruction without having worked as an airline pilot?
There is now no natural route to progress from PPL instruction to Comercial instruction without considerable expense. You need ME time; IFR time and to go into the Sim phase of an Integrated MPL Course at least 1500 hours MPA time. As has been said elsewhere, there is more opportunity to make money by teaching Microlight. For a simulator to be cost effective it needs to run at least 20 hours a day.