With a once daily insulin and three small children, chances are you are at home when you inject. So I wouldn't get a small needle bin for your bag.
is there anything I need to store it is it worth getting a insulin organiser to keep bits in?
You'll need to make some room for the pens in the butter compartiment of your fridge.
The pen you have in use doesn't go in the fridge, you can keep it wherever is convenient for you.
Every insulin pen I've ever had came with a pouch or a small box. I like using those because it holds my pen and some needles, and if I'm out and about I can put the used needle (you can simply put the cap back on for safety) back in the pouch and decant at home.
And you can of course use a different pouch or box and have your children make it all fancy with paint or markers. That way you'll always have a hug with your injections.