Unless you really like and want all this stuff and it would cost more than £2k to replace, I'd tell them where to go, that's a piss take price for second items unless all very high quality, to your taste and needed.
They will either leave them anyway or remove them and you can buy your own stuff.
I would say that asking for money for fixtures and fittings is taking the piss really. Either take stuff with you, sell it completely separate to the sale, or leave it when you move. Before they changed the stamp duty system, it did used to be more common to sell things separately to get round the jumps in stamp duty, eg I had a friend who paid £124.9k for the house and £1k for the kitchen appliances and curtains as this saved her over £1k in stamp duty.
When we bought our first house they left some G Plan furniture, which I hated and didn't realise it was really good quality and I could have sold it
. I think it might have either been burnt or taken to the tip.
The couple we bought off had split up and lost 30% (sounds a lot but it was £42k down to £30k) of the purchase price in a couple of years (they bought at the peak and we bought after a crash) and the man had been obstructive throughout the sale - he smashed the bathroom sink and slashed all the curtains which were horrible anyway, they were a 20 something couple with pensioner taste.
When we sold that house we gave the man who bought it the cooker and the washer because the house we bought had built in appliances.
They weren't worth much, both being over 10 years old and it was much easier to us to just leave them behind. As a single FTB he was very grateful.
We didn't pay any extra for fixtures and fittings when we bought our second house, but it came with some horrible mahogany bedroom furniture which I sold on ebay for a couple of hundred pounds.