Coolant temperature in the red.. engine tray wet.. what's wrong?

[GuidoK]

Mine doesn't look like that at all; is that a pic fro ma Z4C auto?

No, I think its from a 5 series with n52. But its an example of how the sensor looks like. It sits in a hose coupling, either near the rad or near the thermostat. That is the sensor what was meant.

I think I can see some sensor, but it's impossible to access from above, even when you take off the little cover that covers the radiator and fan.

I ran it for 15 mins and took it for a 2 min drive, it looks like there may well be a leak but I can't for the life of me work out where it's coming from. All of the connections I can see and reach were all dry.

Maybe take your fan out? thats quite easy and it'll free up space so you can see the rad. I still suspect the leak being in the reservoir.
That can be hard to see, especially if its on the non visible side.

If there's water leaking, does that rule out that the water pump is the problem?

No, any part that carries coolant can be the problem. Thats why you have to find the leak.