A Lasting Power of Attorney can only be made whilst you have the required mental capacity. If you no longer have mental capacity, your friends or family members would have to apply to the Court of Protection to be appointed as your 'Deputy' to be authorised to make decisions relating to your property and financial affairs.
A Deputy would carry out the same role as an Attorney although there is more formality and cost involved. Also, it is the court which decides who is appointed as a Deputy — you would have no control over who this is.
The Court of Protection process is longer and more costly than the preparation and registration of a Lasting Power of Attorney. A Deputy also has additional duties to report to the Court of Protection on an annual basis with additional supervision fees payable to the Court and insurance costs to pay for the required annual insurance policy.
The Court of Protection will rarely agree to appoint a Deputy generally to make decisions about your health and welfare, preferring one off applications to make specific decisions. By its very nature, this type of application is often expensive.