The "men father children at that age" argument is irrelevant because they do so naturally. Whereas women cannot, not only can they not conceive at that age but their eggs are no longer viable. That is nature.
And you cannot compare menopause to cancer, because cancer is an occurrence that only happens in some people, whereas every woman will go through the menopause and lose the ability to have children.
And yes, if a woman had a terminal illness which meant she was going to die imminently I would say that having a baby would be ill-advised. Of course if she was able to do so naturally then it shouldn't be for us to stop that, but if assistance is required then it is IMO irresponsible to give it.
Personally I don't believe that any IVF should be available on the nhs (although that is an argument for another thread), but in the event that it is, then yes of course criteria should apply if it means the treatment is less likely to be successful, i.e. f a woman is obese/a smoker/heavy drinker/over the age of 40. The nhs only has a certain amount of money, it is totally wrong to waste that money on treatment that is unlikely to be successful given certain factors.