That is a very good idea. As you say drinking challenge is something the Goliath barbarian cant turn down! :)
Thank you very much, I will indeed borrow that concept.

Alright, yea that seems like an easy way to deal with the situation at the same time as my PCs will think they have many options.
Altho Im just a bit nervous (since its the first adventure Im writing myself) that I will be weak on freebasing and "go away" a bit from my notes. And I know people have said to me that "You shouldn't do a homebrew so early being DM, go for already made content instead..".
The first time I was the DM (this will be the second time) I used a already made adventure and I found it having alot of holes in it, also it was way to much fighting and less interaction with NPCs and roleplaying. So I thought being able to write my own after what I like and I know that my friends enjoy would be more benefitual.

How would you "train" on being able to freebase? Is there something i can do in advance online or some kind of exercise to use? Or does that just come naturally when I have DM'ed for a while?

I wrote my first adventure after learning the game with Lost Mine of Phandelver, and I haven't touched modules since. My best advice is, don't freak out! If you know your players, they'll understand that you're new, and they'll be supportive and tell you what went well and what could have been better. Learning to adapt the game for your players is the best way to please them and become a better DM overall. Speaking of that, my second piece of advice is to improvise! Your players will surprise and delight you by doing the unexpected, so surprise them back by rewarding their creativity and making a world that adapts to them and makes their actions matter. The best part of homebrewed games is that, unlike modules, they easily change to fit what the party feels like doing. Take advantage of that.