I agree with mmflynn's 1 2 & 3 answers.
The point is that in Case 1 if you cannot get the clearance to intercept (can't get the radio call in, etc) then you cannot intercept.
BTW
In everywhere but the UK you are cleared to follow the horizontal and vertical profile of the approach. In the UK, if it is an ILS, you are cleared to follow the horizontal profile
is not quite right, AIUI.
If you are told "cleared for the approach" then you are cleared to
immediately descend to the platform altitude and fly the approach as published. This is true worldwide, including the UK. (You still need the landing clearance).
Presumably the controller has to be sure you are within his radar vectoring area, and within the part of it which is
at the platform altitude, before speaking the "cleared for the approach" phrase, because the moment he says it, you are entitled to plummet to 2000ft AGL or whatever
But because he is no longer
vectoring you, he is no longer responsible for your obstacle clearance.
This is why UK radar ATC no longer use the "cleared for the approach" phrase - they don't like the idea of pilots "doing their own thing" i.e. descending to the platform altitude. I read this explanation in a CAA brochure lying on the coffee table at CAA at Gatwick while waiting for my Class 1, so it has to be right
What you get here in the UK are explicit descent instructions, all the way down to the platform, and then a "turn left/right, base leg" and then you report "localiser established". What happens after that tends to be "[descend with the glideslope] contact Tower XXX.XX" where the [] seems optional.