After six months, Simon has learnt a lot about the island and its wildlife and, perhaps more importantly, something about himself too.
"Being able to walk out my front door and be met with all this noise from the birds gives me boost.
"I know for my own personal wellbeing I need time in nature.
"I've always loved being in remote places, although I'm only four miles from Cardiff, sometimes it can seem like a million."
He said the island was "all or nothing" and urged others to make the jump as well.
"Life is short so I put out to anyone thinking of doing something like this - just to do it," he said.
"Feed your inner child and you might end up a place like this."
A big part of Simon's role is preservation, using the land and the rainwater to keep the island going.
"On the mainland we just take everything for granted. If you need food you just go to the shop. If you need water, you just turn on a tap.
"Living on an island the sustainability of all this is quite tricky. For me, Flat Holm is kind of like microcosm for how I look at the world.
"We have to move away from this idea that we have an infinite number of resources, it is just not sustainable.
"We can do it, its not impossible and there solutions are all there, if there is a will to change."