Unless the intention is to go through the mill of the ATP scheme (which you can't due age) then is it really worth the £6.5K for ten or so hours in a generic 737 sim?
No doubt the experience of an AQC will be of extremely high quality tuition which will help in any forthcoming airline sim assessments, but will any chief pilots know what an AQC is when they read your cv?
Surely you would want to keep as much money in the bank if you are about to lose your regular income?
As for the shed rating, I know two people that did it and both eventually got jobs, but that was a couple of years ago.