The first step should be to get a quote from your previous insurers. That will give you a benchmark on how much is will go up. If you have done a TTC course, you will have been given a booklet at the end and in there is an insurance broker that offers good rated for someone who has done one of our courses.
Another place to look is comparethemarket.com. You can put all your details in, with no convictions and get a quote (the tip here is to put the start date in 4-6weeks maximum because if you put you are look8ng for a quote for, say, 6 months time then it will say it is too early to give a quote). You then go back to amend your quote and put the conviction in, finalise the quote and you can see what the increase in premiums have been. They will ask for the offence code - drink driving, dr30 - failing to supply are two usual ones, what your reading was and the length of your ban. You quote the length of the ban you served AFTER a course, if you did one.