There are some bad financial things you can't afford to have happen to you.
Some insurance is legally required for basic living (e.g. car insurance if you want to drive). What we are talking about is something different: paying to avoid catastrophe. If you are a house owner, for example, it would be very odd if you did not insure against its accidental destruction. But what about your future earning capacity? That's harder to decide, and very personal.
So, decide what you need protection against (be honest with yourself). Grit your teeth, buy insurance, accept the reduction in disposable income, sleep at nights.
How to do it? The government's website, MoneyHelper, is helpful.