Another tip you should know....
Order food to go from restaurants--the Brits call it "take away"--and you will save money.
There is a surcharge for being seated in and eating in a restaurant, but that is not added when you get your food to "take away".
Indian restaurants and fish and chips shops are ideal for getting your meal as take away.
Take your meal back to your apartment to enjoy, or find a seat on a park bench to enjoy the view while you eat.
If you have not had Indian food before, you must try it in London.
Chicken Tikka Masala is the classic dish (delicious) but there are many vegetarian or vegan options available.
I recommend having rice, creamed spinach (Saag Paneer) and naan (bread) with the CTM.
Same tip for coffee shops as above.....to occupy a table and sit and drink costs more than if you ordered your coffee to take away.
You will see many coffees on the board on the wall in a coffee shop, offering espresso, cappuccino, Cafe Americano, and more.
The coffee shop workers seem to all assume we Americans want Cafe Americano....coffee loaded with cream and sugar.
All these coffees are a premium charge, just as they are here at Starbucks or wherever.
In England, order "filter coffee". This is just plain black coffee, and costs a fraction of what the more fancy coffees cost. Of course, get what you want....you may want a cappuccino or Cafe Americano, or whatever.
Just know that the cheapest way to get a cup of coffee is to order filter coffee, to take away.
They'll give you cream and sugar packets to take away with you if you want them. So you could just add that to your coffee if you wish.