Insurance is usually cheaper with a provisional licence, as insurers take into consideration that when driving you always have an experienced driver sat beside you. When you pass, you’re essentially a new driver, driving on your own, which means insurers might consider you a higher risk.
If you pass your test, you’ll need to declare this when getting quotes. Or if you take the policy out on a provisional licence before you take your test, as soon as you pass you’ll need to contact the insurer to change it.
Not doing this could cause an insurer to later invalidate your policy. You always need to make sure your details are correct.