Basically some car insurance companies don't cover tools being carried in a car! Business 1 insurance covers you for travelling to a different destination, but not with the tools in the car- ladder, couple of barrels etc So options are-
try and get insurance with Aviva- only company that does it - getting quote is risky as you put all details in and then they know you are working.
Get Business 1 insurance and claim you use customers tools on job and if police stop you they don't read into the policy and find out you aren't covered for tools.
Carry on with domestic and commutation insurance and claim you are off to your mum's for unpaid work- with a few barrels, brush and scrims!