You think this is realistic?
£250 on booze for a WEEK. Do you normally drink that much or is it just Christmas that means you have to have alcohol in excess?
£250 on clothes. Do you not have a large amount of clothes for going out by this point if you spend that annually?
£50 advent calendars when you can buy one for a pound? Why?
£150 pantomime when local places will do it for like a tenner a ticket, if you absolutely must go.
£50 on things to go bang and put in the bin? Why?
£50 decorations? Again, if you've been spending this annually, surely you have plenty by now?
That reduces you by £800. Presents can be budgeted within your means, doesn't need to be hundreds. Same for food. It's a roast dinner and a pud if you want it to be. Even for a party of 10 you could easy do that nicely for £100.
Telling people that £2,000 is REALISTIC when they're worried about money is not helpful and just adds to the pressure.