One of the best things you can have is the ability to improvise.
Essentials are a
*Knife*
because with that you can make most things that are essential,
Also some method of starting a fire a swedish fire steel is brilliant although that does mean you have to find some tinders or make feather sticks.
However is you get one of those air tight food bags from tescos when your out and about whenever you come across some birch trees you can pull off the little curling strips which light very well when there scrapped to be a bit finer. If you want a few bits of rubber inner tube works really well in an emergency.
as for everything else you need
its basicly
Backpack
tarp or tent
sleeping bag
sleeping mat
cooking stove (or oepn fire which i like more)
cooking pots (a billy cans good and a stainless steel mug are good to cook in)
GPS is good but as with all electrical goods faliure is a possibility so a compas and map are essential if your going of the beaten track.
A Nato water flask is good especialy if you can buy the mug that fits around it in stainless steel.
First aid kit
utensils
head torch and normal mag lite (with spare batteries)
Clothing
Wash kit
Food
Then all the possibles you wanna carry.
I got a Bacho saw of amazon which was about £15 i think with delivery. Works really well and is nice and light.
Shelter a good ground mat is essential as its horrible to sleep without one I got a prolite 3 which really works well. If you say you want a hammock its still ideal to have a ground mat as you still get cold even high off the floor.
http://www.postfreeoutdoorgear.co.uk/ is a good one for the mats.
You can buy a australian army hootchie of
www.raymears.co.uk which ive use and there brilliant robust and more hoops that the britich basha.
Hammocks are the best way to sleep but try to buy one where you sleep diagnal across the hammock to get as flat as possible as sleeping like a bannana really hurts after a while.
Flint and steels are very hard to get to work when your trying to teach yourself and its a pain to prepare the tinder so for safety carry somthing as a back up and a flint and steel as an experiment. You can get them off the ray mears website as well.
An axe is good but are you gonna use it to carve alot as the saw if alright for collecting fire wood altough if you wanna use it to split wood its a good idea.
But the small forest axe is about the best for economy of weight carrying and usability. Remember you can use a saw to split wood as well but its not as easy.
Backpacks for overnight hikes about 35 liters is ok for longer a 50-60 is good.
Theres an alright £15 head torch in argos I got it and Its good but its got like 7 bulbs so it takes a while to switch through the settings back to the one you want. I have a small mag lite in my first aid kit as well.
The first aid kit can be bought from boots but you have to add your own items as well a mag lites good. some painkillers and ibuprofen are essential. I like to keep about 10 meters or 3mm cord in there as well which packs up small but can be used on a variety of things from shelters to bow drills. Its good to see what you can fit in your first aid kit and think about making your own one i can write what ive got in mine if you want?
A good pair of gloves works well to keep your energy up when your using your hands to move things in the winter as the heat can be sucked straight out of you if your using metal tools. If you want mittens its alwas good to have a pair of normal gloves with some over mittens as its hard to work with mittens so you can always remove them. But as squidders said its rarely cold enough in england.
Clothing now everyone has there own i love my swanndri bush shirt keeps the wind out and me at just the right temperature there alot of different stuff a tilley hat keeps your head reasonably dry and some fjallraven forester trousers keep your legs dry but they do make a bit of sound when walking.
I've probably made this really drawn out and very boring but I think its worthwild taking the right kit.