Well, your 5000 hr guy is going to have to do the same course as you, and cough up the same £4 to £5k in order to earn just £10k pa on average.
Now, I would doubt that too many will take that option in order to pay (or not pay) the mortgage while they wait for things to get better. However no doubt WWW will give us a gloomy rebuttal on that idea and give you a dozen reasons why you haven't a hope in hell!
It's a bad time of year to be looking for an instructors job, and most instructors are now going to be there for a while longer than was perhaps planned.
Go for it, but please don't degrade the profession by offering to work for nothing. Things are bad enough without that as well!
Good luck