After even more confusion, let's bring this down to a straight answer to the exact question, as asked…
"Is there some superior quality.."
No. Salt is salt.
It seems people in comments below have been so preoccupied with whether or not we have kosher salt in the UK or EU - we don't - that they've forgotten the entire point of this answer…
There is no "best salt".
All salt tastes the same by the time it's mixed in with your food[1]. Use it by weight not volume if you ever change your crystal size.
[1] this may not be true for iodised salt, but I don't think I've ever tasted it. It's not unobtainable here, but is very much a tiny slot on the salt shelf in a supermarket.
From comments again - apparently iodised salt has a metallic overtone.
I also just discovered why the UK doesn't need iodised salt - they 'fixed' the milk instead - https://www.bda.uk.com/resource/iodine-deficiency-in-the-uk-dietetic-implications.html
Pro cooks in the UK have been using table or cooking salt for far longer than we've had cooking shows or internet recipes. Until the invention of the interwebz we'd never heard of kosher salt. [This turns out to be because it's a US naming convention to indicate 'purity', apparently because most other US salt is iodised.]
Salt is salt, give or take the odd anti-caking agent.
The only difference in salt "types" is the volume/weight ratio… & price.
UK prices…
Table/cooking salt — £1 per kilo
Kosher salt [imported] — £7 - 15 per kilo
Himalayan salt [another outrageous money spinner that can only be qualified as "they saw you coming & laughed"] — £33 per kilo.
They all taste exactly the same.
You get used to the quantities you need in a recipe by experience. If you read an international online recipe, then whatever value it gives for added salt, use your prior experience - unless one or more of the ingredients is particularly salty, it will be the same quantity as you always use.
If it says use kosher salt & you only have table, then don't measure in spoons, measure by weight, or drop the usage by 2/3… or, as many recipes say - "season to taste"… a bit to start with, check it part-way through, make sure it's right at the end.
There is no such thing as a "best salt".
Don't believe the hype.