Thanks everyone :)
He is still growing out weak hoof, it takes up to a year for their feet to really be great. I've been trimming him for the past more than 3 months because Mum's been out of action and well I'm not the most experienced (or trained) farrier, but I'm for sure more reliable than most of the farriers in my area! At least I actually turn up to trim. We know a brilliant barefoot farrier with 2 years of university level training in hoof trimming... she is fully qualified and always up for learning more. But my god she charges like a wounded bull, and I have two horses. I could have BOTH of them done by nearly any other local farrier for what she charges for one.
The boots were sort of a meanwhile thing, while we get his feet sorted out and nice and strong. I think I will start feeding him hoof suppliments but I have to get paid first!