Dont take this the wrong way, but lets have all the facts before usefull advice can be offered please. Drink driving you said -DN10 or higher. And now an IN10 no insurance possibly a speeding as well from your discription?, dangerous driving. Whatever, it must be a totting up TT 99 to get a 3 year ban. Did she have permission to take his car?
My advice is Your current insurer is your first call. She wont be the first banned driver they have spoken to, believe me, they do it everyday and wont be shocked.
3 or more new convictions at a new insurer will often be an automatic decline.