Fix my tap please

The last couple of taps I fixed used a valve/cartridge thingy. I just replaced the whole valve as it was only a few pounds from somewhere like screw fix. The whole unit just screwed in and out. One was a balls to unscrew as the limescale buildup had practically welded it in place. Unscrew the cover circled and see if it’s a valve or not. IANAP.

Youll need to isolate it, remove handle, then get into the gubbins and take that to a plumbers merchant or B&Q. Not all tap parts are the same and there are loads of variation in threaded lengths etc. Last two sets of ceramic cartridge replacements have been bodging parts from the new one and chucking alot of the new cartridge away.

In the old days leaking from the spindle just meant repacking the gland with PTFE tape or similar, no isolation necessary for that job. It's probably an o ring on a modern tap, but as suggested above safest to isolate, strip then take any bits you're unsure about to a DIY shop.

IANAP either, but I've dismantled one or two taps because we have a bit of trouble here with limescale. That doesn't look like the sort that takes a £5 ceramic cartridge - as you suspect, it'll be washers or whatever around a spindle. Washers are as cheap as chips, but gotta be the right size.

I also find that cartridge size is an issue - you need to whip it out and measure things like diameter, length of cartridge and length of spindle.
FWIW, I bought a new tap last time as it was getting on a bit. It was easier than to replace the cartridge as I had the time before.

I would try to identify it and replace the cartridge if it is a ceramic disc tap.

If it's a branded tap, you might have joy getting a new cartridge. If it's a cheapy from abroad, just scrap it and replace the tap.

Look in the Tap magician site if you know what tap it is.