If i wanted to pick up the najdorf or dragon how hard would it really be?

How well do you want to play?

Well, you should give the Najdorf a go. You can choose simpler lines if you want less theory.

You should pick the dragon.   The Najdorf relies on long forced variations and the first one to vary from theory loses.  Often natural looking moves lead to a disaster.   The dragon is easier for Black to play than for White.  You need to know a few themes (like the exchange sacrifice on c3).  If you don't remember the book move, you can follow general themes in the Dragon.  Leave the Najdorf to the professionals.

Every Sicilian variation has tons of long lines to memorize. Look at a bunch of them and figure which ones look like something you'd want to play 30-50 moves in.

It is very difficult to learn how to play a big opening.

Just learn to play chess.

If you're into memorizing, there are long lines that can be memorized.  But, at OPs level there is no point memorization,  since your opponent won't remember past move 10. 

How hard is it to learn the sicilian

If your opponent plays it often & knows the lines well then it is quite hard !

But if you like to respond to e4 in different ways then you have to learn the sicilian do you not ?

The najdorf can be very complicated but loads of people choose the dragon as black.

wow

In one way it's very simple. Your opponent plays 1.e4, you respond 1...c5 and just like that, you're playing the Sicilian! In another way a super-GM can devote years trying to completely master the Sicilian

It is not worth the time. Loads of theory and then your opponent play 2.f4 or 3.Bb5 instead. If you like sicilian type of position go fot the Kan instead.