Okay recently I've completed my second Kai Tak approach. However, when I get told what runway I'm landing on, they always tell me to do ILS Runway 31.

I want to land on Runway 13 so I can do the 'infamous approach' but when I request RWY 13 from the ATC, they tell me something like: "ILS approach 13, circle to land runway 31" then a little while later "enter left downwind"

How come they tell me this when I requested to land on RWY 13? - Also when they say ILS approach runway 13, then tell me to land on runway 31, what do I do? Do I set an ILS up for runway 13 but not use it?

It's quite confusing.

PS: Oh and another thing, if I enter left downwind, do they give me clearance to land? Should I just land w/out their clearance?

Help would be appreciated!