Freshers week time off

I'm starting uni in September and will be living at home about 10 minutes away. I plan on attending the majority of the freshers week events however I have an orthodontist appointment on the Wednesday and a driving test Friday and both of these days will be my first 2 seminars/lectures at the times my appointments are. I've tried to rearrange my orthodontist appointment but they don't have any more appointments until November and I obviously can't move my driving test. Will it be too much of s problem or will I be able to catch up on stuff?

(I'll be able to attend the first half an hour of the first lecture/seminar and will probably be 20 mins late for the second)