Hey there newcomer! (and maybe future buddeh)
Firstly a late welcome to roleplaying, you’re taking the step all of us roleplayers have gone through one point in our roleplaying time!
Stormwind is currently one of the main RP hubs to be around on the Alliance side, think Darkshire might be second but I haven’t done a lot of public roleplaying myself lately.
You mentioned that you cannot commit to a RP guild, which is unfortunate as I’d say that’s how I really started learning how to roleplay in WoW. Maybe you could find a roleplaying guild here that could fit your RP-time to spend per month.
I’d also say try to spectate (or even attend!) public events. Lot’s of them can be found on this forum and they are really fun to join.
Last but not least, do know that it was scary for almost everyone who started roleplaying here during their first couple of times. That fear will fade away in time, we were all noobs at life when we were born. It will feel new, exciting and scary… but in time you’ll be roleplaying like it’s cycling. If you need someone to guide you in-game as well, try sending me a message in-game. Hope to see you soon on Azeroth 
Edit: Not a necesarry addon but Listener has really helped me out. The addon marks your name when used by other players in chat channels.