I can be a real running bore, but I'll try to keep it short!
26.2 miles is a long way. It is possible to train from scratch and run a marathon but IME must people who do that burn themselves out and never run again.
To enjoy it properly, IMO, you need at least 2 years of consistent running and a few shorter races under your belt before you start training for a marathon. Even then you'll be following a get round programme rather than aiming for a decent time, but that's OK.
As for the training. Don't under estimate the impact it will have on the rest of your life. You'll follow a programme which will probably include up to 7/8 hours of running a week, so you know how much time you have to give it. What I didn't realise was just how useless I'd be in between times. All I wanted to do was eat and sleep and somethings that was all I was physically capable of.
Also the recovery, I think it took me a year, mentally as much as physically, to recover from my first. When your entire life has been building up to one day the end can be hard and you're dealing with it physically depleted.
So, in summary, yes absolutely completely worth it. You'll never forget it 😆
Getting a place isn't easy though.