The FAA insists on maintaining the circling altitude until established on final track, which means that for a large airplane you will be out a long way on final or else you will be high on glidepath. ICAO allows descent when on the normal glide path, which usually happens on base leg. Am I right about this? The subject gets confusing.
I also believe that if you are circling you are not flying IFR any longer, but are visual. This means that visual limits apply (in sight of ground or water and clear of cloud). It seems reasonable to me that flying in and out of the cloud base makes no sense. Better to drop down a hundred feet and maintain visual.
Many of you believe that a circling approach should not be flown in a large airplane, and some even maintain that an NDB approach is not on. If you never practice them, I suppose you should not try, but for the real pilots out there (there must be a few left) don't pay those people any mind. When the weather is bad and the aids have gone down due to power failures, the circling approach might be all that is left to you. You will feel a lot better knowing that you can handle it than to be in the state of panic those 'experts' will be experiencing.
You can practice the circling/visual/non-precision approaches on line in good weather, or in the sim (ask the Instructor!) in any weather or vis you want.
A diversion might not be available to you, and even if it is, you could be faced with a worse combination of weather and approaches at the alternate, and in addition you will have minimum fuel.
This is yet another example of attempting to regulate safety. It will never work.