Well... The first thing you must consider is that you are using a good oil. An oil change could be a good idea before the trip.
Secondly, make sure that your coolant liquid is strong enough and doesn't freeze.
Thirdly, make sure your battery is alive and kicking - if not get a new one.
Then, when it comes to starting your MINI at extrmely cold temperatures I have good news - I started my MINI last winter in northern Finland at a temperature of -33 degrees celsius without any problems (a good battery helps here).
However, you will make your life a lot easier if you install an electric preheater to your MINI and use it for couple of hours before you start. More info about preheaters can be found at
www.calix.se and
www.defa.no just to mention a few. Furthermore, by using preheater at temperatures below +5 degrees (YES, plus 5!!!) you will reduce your fuel consumption by roughly 1 litre/100 km so it's even environmental friendly while saving some money on the side!
Driving in extreme cold in a MINI is a breeze at least in my opinion. There's enough power in the heater to keep the car warm inside and seatheaters will help a lot also...
However, there are couple of things which are a bit annoying at cold temperatures: 1. The gear lever knob gets very cold and you have to drive with your gloves on. 2. Gearbox and suspension seems to take ages to warm up below -25 degrees so they are stiffer than usual. Other than that no problemos at all!
Oh, one thing more... Make sure you have enough washer liquid and that it won't freeze!
Have a nice wintertime on your MINI!
n.
PS. If you can't find out the info from your dealer there, I could check out the dealer here in Finland what they say about proper oils, anti-freeze levels etc.