Food and Drink is also important when out at night, because you are so far away from home and in the middle of the night no stores will be open so it is important to be stocked up on important food and drinks, if you don't have food and drink for so many hours while you would usually be sleeping your body will start to slow down and you will become dehydrated and will possible get headaches and make the night less enjoyable and you will want to go home, this will also knock your concentration when driving.
A lot of people use Energy Drinks for a quick boost and they are very popular in Night Photography and Urban Exploration. The only problem is, is thats all it is, a quick boost, after an hour your body starts to crash because the quick sugar and energy rush is fading and your body is lacking the calories it needs to carry on going, so you will have another energy drink to keep you going again, you'll be having them all night and not be feeling great after it. I know a lot of people who are addicted to them. Mixed with a caffeine tablet such as pro plus it can be quite a dangerous combination as well as drinking too much coffee.
As I was just stating Caffeine Tablets are not a great source of energy not in the long run anyway, you will be popping pills frequently and mixed with energy drinks that much caffeine isn't particularly safe.
A thermos is a great thing to have back at the car with either Tea or Soup in, come back to the car and it's cold and your tired best thing to have is a cup of tea or a cup of soup.
Come in every size and can keep things warm for up to 12 hours.
As far as drinks go a bottle of water is pretty good, refreshing and stays cool in these cold UK temperatures.
Nothing beats a good old sandwich, put whatever you want on it, bring as many as you like and enjoy! who can ask for better, also saving you a bit on the money front so you can be using it for fuel to go to better locations.