[Closed] Insurance Renewal - Changing Excess

I live in a row of houses with a shared drain which blocks every year or so - plumbing company unblocks and the cost is shared amongst us - approx £20 each. Last time they used a camera to examine the drain and it was full of tree roots. They recommended clearing the roots and applying a new plastic liner - cost to be recovered from house insurance. I currently have a large excess on my house insurance but the policy is coming up for renewal. So is it illegal to reduce the excess if I know I might be making a claim? Nothing is currently agreed and we've had no paperwork/quote from the plumbing company. The work might not even take place as we'll have to get agreement from everybody to go ahead.