Windy, you have already mentioned some of the extra's, most of the rest are luxuries! a small stove and brew kit and of course cup help, as does a small saucepan and/or fry pan, but it's all down to how much scoff you peronally need. I think most of us eat to much when fishing, we are hardly burning the cals bivvied up on a gravel pit!
What i tend to do is when making a nice home made Stew , curry or similar is to freeze a decent portion in one of those tupperware containers, this type of meal can then be heated in the pan, it's far better than make do ready meals in my opinion!! i usually have this as an evening meal, a few biscuits with a brew does me during the day.
You may think why is he waffling on about scoff? if you feel comfy on a long session you will fish better and you probably know what tackle to take.
A decent bergan is a must, and practice packing it so that you know where everything is...in the dark.
Take a nosey around outdoor type shops for things like stuff sacs for your sleeping bag and clothing, it all helps to make space. They sell loads of useful gadgets, but watch the prices, you can always improvise on things like containers.
One thing that is so easy to forget is the water, but only take enough for your needs...it's heavy!!
If i am definatly staying put in the one swim for a while i do like a little reading material, usually fishing related, (anything else and i might get too homesick...if you get my gist!!)
Make a tick list of what you need and use it each time and then you can adjust it to suit your personal needs.
Hope that helps a little mate.