So, as you read, this is my absolute first mod, im hoping it for it to be like 30-45 minutes of gameplay spanning across 2-3 maps. Due to many sleepless nights watching Adam Miller-The Architect Of Games, many sleepless nights playing all kinds of HL2 mods, and replaying the trilogy like 11 times, Im pretty confident I can design a somewhat decent level, but that's the problem, "design" and im worried If I have the skill to pull off everything I want in Hammer. Well, only time shall tell.
First Mod
If you're worried about whether or not you can make a full mod, you probably shouldn't be advertising one. Not to discourage you, quite the opposite, but it might be better to practice mapping on your own for a while instead of putting pressure on yourself to develop a full campaign. People new to modding often do that and get burnt out, so just have fun with it until you have something that you're really proud of.
You make a really good point but im not planning on this being a thing I do 24/7, im expecting this to take like a month at minimum, and honestly if my progress will keep going as good as it is I think it will turn out fine. My biggest issue with starting projects is that im bad and I dont have the patience to, but I noticed Hammer is so easy to work with and it's so much fun pressing that F9 button and seeing how good your level is.