There are three big factors that determine how much cover you’d be able to take out:
You pay your agreed monthly premium either until you die, or until you reach 90 and then when you eventually pass away, the policy will pay out. Bear in mind that your policy may have a deferred period, typically 12 to 24 months. The amount paid out during this period will vary by provider, so be sure to check the policy details. If you’ve set your policy up in trust it will go to whoever you named as a beneficiary.
Over 50s life insurance are purely insurance plans and as such have no investment element to them meaning they will never have a cash-in or surrender value - so if you stop paying your premiums you won’t get anything back.