The transfer from Sofia airport to Borovets is no more than an hour. You can use the road past the Iskar dam if you want a scenic drive or else the motorway via Kostenetz
Having doen this journey on a few occasions it will take from an hour upwards, depending on the road conditions, and the big fat truck going to greece that i always get stuck behind. I would not go via Kostenets myself, the road back is the pits. If you said an hour and a half youd be about right.
Lyndsey, don 't use normal suncream but look out for the ones special for ski: they protect your face against the cold too. Nivea ski for example has 2in1 for the lips + face.