I am sorry this has happened to you. How things go, really depends on who you were insured with. You need to read the small print. What happens when a car is a writen off, do they cancel your insurance?. Let say you have a 12 month policy, and have 1 month left, before renewal, it is n't an issue. However, if you just renewed, you loose 12 months worth of policy cover. It depends on insurers. Idealy, they should continue the cover to the new car (or continue if you buy it back). It is a pain when they cancel the insurance, so you can't drive your car to see other cars and you can't borrow other people's cars. You become carless!
Sadly, something similar happened to me.
In my case, it was n't worth claiming, so I got it repaired myself, but I was asked to a new MOT.