When I compared I compared similar level hotels abroad, on same basis, with similar level hotels here.
So last summer me, dh and Dd went to France. We travelled by train and Eurostar to Paris. We stayed in hotels in good central locations in 4 or 5 locations using the trains to travel and a two day car hire, ate out each day.
This year, dh and I are going to Cornwall, driving. We are staying in hotels on the way there and back, plus 3 locations in Cornwall and `Devon. We will eat out daily, at the hotel or elsewhere.
The accommodation cost is dearer here and tbh not all of it is as good a standard simply as the choice was greatly reduced. Demand is far outstripping supply, so even booking several months ago there wasn't as much choice.
The accommodation for 3 adults in France was £1900 for 14 nights.
The accommodation for 2 adults in England this summer is £2840 for 14 nights.
The travel costs will be cheaper. The trains cost for 3 people last summer in France about £1200 (so £800 for 2 plus £200 car hire)
Our car is electric so fuel costs will be cheaper this summer but I do need to add parking costs on. I'm not yet sure what these will be. Plus any taxi costs if we go out at night as the accommodation isn't as centrally placed - again due to lack of choice remaining.
So France: £2900 for accommodation and travel for 2 (would have realistically been less as some accommodation was 2/bigger but I've left full cost for ease)
And England: £2840 before I add travel/parking on top.
Food and drinks will likely be similar costs per person.
Not sure about entertainment - some of the potential days out are fairly pricey but we may/may not go depending on how busy it is.
Including accommodation, travel, theme park and vineyard/caves and other entertainment our total cost of holiday (minus food/drinks) last summer cost us just over £1300 per person.