Going absolutely basic, you need:
Crockery, cutlery, cooking utensils, tea towels
Mattress
Bedding incl duvet
One more pair curtains, 2 curtain rails
Table, 2 chairs
Sofa or armchair
Drill and basic tool set
Cooker or hob & air fryer
Microwave
Washing machine
I'd suggest getting the first six items from Ikea - delivery's £40. Buy cheap because you will be replacing them as you move forwards, but everything from Ikea will last a good five years.
You could order some storage from there to be delivered at the same time, if you've got an idea of what you'll need to begin with. (My flat's fully lined with Billy bookcases and Malm drawers!) You might also want to get a rug or something.
The other things you can buy second-hand or from Ebay, Argos, etc.
Move an amount from your savings to an easy access account for the stuff you will realise you need (coat hangers, bottle/can opener, cushions, hooks, all sorts of things) and a TV if you watch it, your internet service, more things depending on your lifestyle. I'd say £1k but everyone's budgets and needs are different.
Have fun! Happy new home!