You can easily get cover for working at home. But usually work is excluded from domestic policies; particularly third party liability.
Obviously the liabilities vary, if you're doing prototyping of fireworks in your garage then it's a little more risky than coding!
Insurance isn't always priced solely by risk; work-from-home insurance probably reduces claims for many people but that doesn't mean you can't charge more for it.
It would be interesting to know how occupier presence varies with claims made.