How do I bathroom / kitchen / extension? etc.

Depends what you want. There are some LVT offerings around £20/m² at the moment.

LVT

I've got 18m2 of this cork floor tile leftover from recent works (the company sent a different fitting system in error and I've ended up with a load of cork floor tiles left over) that I could do a good deal on?

laminate

Commercial grade vinyl. Something like Polyflor. Much like colour flooring co , but cheaper and harder wearing, <£30 sqm . You'd need to screed the floors though . Works in bathrooms too

https://www.coversmerchants.co.uk/ted-todd-clevedon-narrow-herringbone-flooring-450-x-90-x-14mm-b43246

This worked out at about £40/SQM, the list price comes down a lot if you set up an account. Its Ted Tod's trade standard and can have knots, but it looks really good. Laid it floating, not sure my back will ever be the same but very happy with it.

https://www.instagram.com/p/ChXyB_zKo8k/?igshid=YmMyMTA2M2Y=