Practical advice:
Take cover till the age you will practically earn and will have dependents on you: age 55-60 (max). After you stop earning at say 60, your death would not make a financial difference to your dependents, so having cover isn't useful.
Premium payment: Pay it till the last day of your cover, don't prepay till 41. You pay premiums as you enjoy the insurance cover. There might be a day when you don't need the plan, a better plan is available etc. Why prepay for the plan by 41 (unless it is significantly cheaper)?