Outbuilding Insurance

TheFair

We’ve built an outbuilding that’s 29.5 sq.m down at the end of our garden. It’s made from block work with a PVC membrane roof, double glazed etc. It has power and plumbing with its own consumer unit and shower room. It is, essentially a Studio.  It was built under planning and has cctv/Alarm etc. 

I want to get it insured, but the one quote I’ve had from Henshalls is more than double the cost of my current home insurance policy. However the rebuild costs will be north of £60k so it does need insuring. What has anyone else done about insuring permanent structures in their gardens?  Most insurers only seem to offer £15k cover for outbuildings.