Try Floyds Direct on the internet. Competitive prices, cheaper than the Post Office.
You will not do so on this site but before you do I would advise that you look around at the various insurances available because the one that you are considering may not be the best or cheapest... Nei.
Try post office they are quite cheap ive used them couple time.
Try www.moneysupermarket.com where you can get a range of quotes to suit your requirements and purchase online. Don't bother with confused.com as they exclude cruises from their cover for some strange reason.
Try post offic.
Try Sainsbury's for your insurance quote. We received a quote from them for £39.00 for the year. Hope that this helps.