If you've had an accident don't get any repair work done until you have cleared it with your car insurance company first. It is possible to choose a car insurance company who have agreed car repairers, to save you driving around getting quotes. They normally gaurantee their work also.
Remember giving false information or leaving out vital information to get cheaper insurance is an offence and will ultimately leave your policy null and void.
Making a claim will not automatically lose all your no claims bonus. Most insurers will relegate you only two years meaning if you had 5 years no claims then you would still have 3 years.
Until your insurance company issues you with a cover note or a new policy then your car is not insured. That does not mean you need to have recieved your cover note. Many comapnies, give you instant cover, where the agreement is there imediatly.