Woah, I was doing something like this a few years back! It was in the private medical sector so I think it will be a little different, but that sounds like something a bit more engaging and hopefully a bit more methodical; a nice change from your more turbulent jobs.
I will offer one piece of advice: be prepared for any sort of patient! As it's dealing with insurance claims, you're going to definitely get some very difficult and angry people, so just try as hard as you can to remember that they aren't angry at you they are angry that for X reason they're not receiving that claim!
I wish you all the best for it and definitely do keep applying, backups are always good.
Awh thank you, it's been a struggle but a few things are starting to come to a close now, so over the next few years hopefully things will sort themselves out in time.