Hi OP, I'm no expert but this is a good article. There are a lot of different types of life insurance, some of the most common are:
-Death in service benefit linked to an occupational pension - usually in the form of a lump sum and a 'survivors pension' to be paid to the nominated beneficiaries. Your DH/DP may well have this through work already but a few things to bear in mind, he would need to be an active member of the scheme when he died for it to pay out, so for instance if he had a critical illness which meant he left or lost his job, it wouldn't pay out. Also, although the lump sum amount may sound large (4 or 5 times annual salary is not unusual), actually if you have a large mortgage, young children to bring up and limited earning capacity yourself it might not be enough, and the survivors pension can be quite small. Also on a basic level he needs to check he has nominated you as beneficiary, as you are married you should receive the money (unless he names someone else as beneficiary) but obviously it will be easier if you are named...
-Decreasing term critical illness and life insurance cover - you typically take this out at the time you take out a mortgage, and the idea is the policy pays off whatever is left on the mortgage at the time of death or very serious illness to prevent the house having to be sold (do check the T&Cs on this, I've heard of cases which you'd think would easily count as critical/very serious illness where the policy didn't pay out - they'll also usually health screen you/DH and exclude any illnesses where there's a family history - my mortgage company excluded all cancers, strokes, heart diseases and neurological conditions from mine due to crappy family history, which to me basically made the policy near worthless as the vast majority of likely causes of critical illness were excluded aside from accident or act of god [anger] ). Again see above, even if you do take this kind of policy out you may need additional cover as even if the mortgage was paid off, could either party raise the young children alone without additional financial support?
Lump sum cover, this pays out a fixed amount in the event of a death, do not get this muddled with the decreasing term cover. You'll need to think what a reasonable pay out amount would be as obviously the higher the amount the life is insured for the higher the premium. Also again being older or having a dodgy family history likely to mean higher premiums.
I'd highly recommend reading the article I linked to as it goes through a lot of what you need to know...