You should be able to get a quote from your original company. You will be able to get cover from somewhere, as it's a requirement. If you get two refusals in writing then you can apply to the Insurance Federation who will force the first person you contacted to provide insurance. I probably have some of these details wrong, but I'm confident you cannot be refused by everybody.
I'd say you would have to notify claims for up to five or six years, but only provide the information asked for... don't volunteer any information.