How do I bathroom / kitchen / extension? etc.

DBR No bottom track but sometimes have a groove in the bottom of the door and a pin poking up from the floor in the jamb at the “entrance” to the pocket.

This is what we had when we moved in, but I ultimately made the only sensible decision that the only good pocket door is one that's been sledgehammered out of the already small aperture and sits leaning, broken, against a wall in a mould-covered downstairs toilet we never go in.

franchi the lock store have a few you can try out in their holloway road store

We're going with this https://www.fhbrundle.co.uk/products/41002__Sliding_Door_Kit_for_Solid_Door_Satin_Polish_304_Stainless_Steel