CBD is everywhere in the UK now: oils, gummies, drinks, balms, coffee. It's legal, it's not what gets you high, and it's sold on a lot of big promises. Here's the level-headed version: what it is, what the evidence does and doesn't support, where it stands legally, and why what's on the label often isn't what's in the bottle.
About everyday CBD, a different and far weaker thing than the cannabis that gets you high. For cannabis as prescribed medicine, see Medical Cannabis; for the plant itself, The Plant.
The non-intoxicating cannabinoid: what it is, and the honest gap between the evidence and the marketing.
Broadly yes, with nuance: the trace-THC rule, the "novel food" status, and what the 0.2% figure really means.
A sensible dose, who should avoid it entirely, and how to buy something that’s actually what the label says.
Shelf CBD, the licensed CBD medicine, and prescribed medical cannabis: three things that get blurred constantly.
CBD is only one compound in the plant, and the full chemistry is in What's in it. If your question is really about cannabis for a health condition, that's the Medical cannabis page, and a conversation for a doctor.