I have recently started my first job out of university. In my first week, I had to travel to London (HQ) for 3 days for training. The annual Christmas week, also in London, is currently being planned. It involves lunches, a team-building day, party - nothing too essential.
I have a very sick family member, and really don't think I can be away from home so close to Christmas. I just don't think it's worth it should anything happen, and particularly as this trip doesn't seem essential. Although the trip in my first week was difficult, as it was arranged for the sole purpose of training me I felt I had to go.
Flights, etc. for the Christmas trip have already been booked. I have checked the cancellation policies of both the airline and hotel and the company don't stand to lose any money should I cancel. I don't want to rock the boat as a new hire and cause bad feelings.
How should I tell my boss (who I've been getting on very well with), without any major fallout/risk of losing my job?