Glad I'm not the only one to do it
Get in the car 10/15 min before you have to leave, wait until the temp gauge it's just below or at half way and than drive away ( changing at around 2k for the first 10 min)
In relation to your problem........... Soryy I've no idea
Not wishing to open a can of worms here, but there is another chain of thought that waiting for the engine to warm up is a bad thing. The logic is that if the engine sits at idle then there is not much oil pressure which translates to low lubrication around the top of the engine. Therefore, driving the car, but keeping under 2-3k rpm increases the oil pressure and avoids this problem. I'm no expert, but that makes sense to me.
Regarding the noise, it definitely sounds like something loose, my K1 did this until warm - turned out to be a bung rattling.