The real picture, which having checked, also applies to The USA, Australia and Canada is that it is the patient's decision but there is a slight proviso to the Acme statement.

The clinicians carrying out the procedure must be satisfied that the consent is valid and there would not be complications as a result. (The more you have, the worse the prognosis.)

Talk of secular humanists is an irrelevant sideshow. If you are a member of a religion and accept a doctrine that requires control of your decisions, that is, perversely enough, your decision. Psychiatric colleagues of mine may argue your judgement is impaired by social conditioning but the reality is, it's still your choice to observe controlling old men or not, even if you do confuse their rhetoric with moral guidance.

Moral guidance may have a purpose before getting laid but it is superfluous afterwards.