I don't think it affects you too much, sometimes it can be better if you're like "woah, this guy is so cool!" because you have never seen him before. You might get some base knowledge, but I don't think it's necessary. It's just an extra so to speak
Also, the old ones, episodes are MUCH longer. Like...6 parts?
If you really want to see the episode where he first appeared, here's the wiki link.
The Abominable Snowmen - Wikipedia, the free encyclopedia
I don't think you have to watch them, but it can be fun if you do sometimes.