Instructing - unpaid? You what?!?!
Working for free as an FI(R)? Not sure how viable this would be... I started work as an FI(R) in April this year. I instruct 7 days a week at two different clubs and average 40 hours flying a month. The average day is 10 hours long and may consist of 2-3 trips if I'm lucky. A lot of downtime between each trip and a lot of briefing/groundschool which you don't get paid for.
If all I could have got was unpaid instructing work to start with I probably would have done it. But you have to ask yourself this. What will it feel like working for free 2 months down the line?
I think you would very quickly come to resent instructing for free which would probably make you a worse instructor. You also have to consider the dis-service you would be doing to the instructing community who are trying to cut a living doing it.
On a positive note, it is a thoroughly enjoyable way to make a living albeit a hard one... Good luck finding a job in these difficult times if you decide to go for it.