I tried to write a linked list a while back and it took me like 3 hours. I was wondering if the recommendation would be brush up C first. Although, like you said, with enough motivation it'll just fold into the above curriculum
I bet you could rewrite it in under an hour now. Programming in general is a lot like hacky sack. If you don't do it that often, it seems difficult, but you get a few kicks in. The more you do it, the easier it is.
I would brush up as I go because the motivation would be this book itself.