I don't understand this story. It's really badly presented:

Hopper dishonestly made a false representation to Aviva and Old Mutual Health that his “legs had been amputated because of illness rather than self-inflicted injury”, the court heard

Aviva is a private health insurance, Old Mutual Health doesn't seem to operate in the UK, only in Kenya, Rwanda and South Africa? Either way, don't insurance companies legally have to pay even for treating self-iflicted injuries requiring amputation?

In April 2019, he used dry ice to freeze his legs to the extent they were no longer viable and required amputation.

The amputation had to happen, else he would have died. Hell, I'd even argue the freezing occured due to mental illness so he misrepresented it only by claiming the amputation was physical illness. How is the cause even relevant for a health insurance?

After the amputation, he made claims to the insurers that resulted in payouts of £466,653.81. He spent the money on a campervan, a hot tub, wood burner and building works.

These are health insurances. Not life insurances or similar that would pay you for losing your legs. Don't health insurances just cover the treatment (amputation), recovery and prosthetics? Sure they can get expensive - a six digit figure seems like a lot still but not fully implausible - but why would you get a "payout"? Health insurance would only cover bills.

Surely it can't be insurance fraud to harm yourself and then make an insurance claim for the recovery, right? Otherwise literally everyone who survived a suicide attempt would have to cover all associated expenses.

So where did the fraud part come from?