@TizerorFizz @SocialistSally having lived there till recently--here's my tips
Coffees- if you use the espresso house chain which are lovely (and everywhere) a large one there at around £6 is enormous. I used to carry round a washed takeout container and split one. It sounds enormously mean but honestly was just the right size then for 2.
If you go in the summer/early autumn, places like Broens beer garden (by Nyhavn and just over bridge in Christianshavn - or Reffen (you go on bus or boat ) are brilliant- huge outdoor food stall areas with seats and DJs etc and not drastic . Outside of those times Tivoli food hall is good - an indoor food stall place- you get something decent for about £12
The aforementioned Espresso house do fabulous ham cheese and mustard focaccias - they are huge and around £7 -
The hot dog stalls are amazing - especially the one at the round tower- big and come with crispy onions, pickles and remoulded at around £5 to £6
I recommend the following for meals
Magasasa - (meatpacking) - around £28 each will get you a massive high quality oriental meal
Mother- fantastic Italian- again about £28
The chain Vivaldi - pub/bar type food in nice setting. The Frederiksberg one is good - about £30 for 2 courses - good standard
The madklubben chain (they have about 10 all themed differently) do great set meals - I like Tony's down by Nyhavn. 2 or 3 courses around £32 . High standard
Mad&caffe (3 or 4 branches) do fantastic breakfasts for around £12 - you can pick a set number of items from hot stuff to pastries or eggs etc - great coffee too.
In theNorrebro area
There are lots of good ethnic restaurants- we've had good quality meals for around £15
I cannot deny wine is expensive out but I've never had a rubbish glass- about £12 a glass or £45 a reasonable bottle. It is suprisingly cheap though in supermarkets and you are allowed to drink your own outside - so can be suprisingly nice to sit by canal etc or park- and you rarely see anyone plastered - even though it's allowed.
Beer isn't cheap either but not much different to London prices and reasonable in supermarkets
Hope some of this might help.