I think you should contact a motor reassurance company (aka motor insurance broker). They have access to more than one insurance company and therefore can provide you with more options and better quotes for you to choose. I know because I went with a broker recently and manage to drop my premium about 1/3 with basically same coverage and excess amount.
When talking to the broker, you will need to tell them what is important to you. e.g. excess amount, dealer workshop vs authorized workshop, NCD protection, etc... They can in turn provide you with a quote that meets your need.