Suitable insurance?

Hi, about 6 years ago I moved into a 1970's bult detached house in a small close in Scotland. Initially, the house was in need of refurbishment and I didn't have a lot of possessions, so I opted for the minimum building insurance to cover the mortgage requirements. Now the house is in good shape and I have filled it with the usual types of furniture and electronics. Additionally, a neighbour recently reversed into the fibreglass, up-and-over door of my integral garage. So I'm thinking of replacing it with an automated roller door. In case anything similarly untoward happens in the future, I'd like to get the house and it's contents adequately insured. I don't know much about insurance but I have the impression that there are relatively cheap policies, which place restrictive conditions on claims and quite extravagant, high cost policies which are more financially responsive. How can I ensure that I achieve a quality of insurance that is somewhere in the middle of these 2 extremes? TIA Mikey