In the UK you have an allowance of £12,300 per year on capital gains and £2,000 for dividends. If you earn less than that (or have the shares in an ISA) then you don’t have to do anything or pay anything. Doesn’t matter where shares are from.
If you make above that, you should be using an ISA; but if you don’t, you just report in a self-assessment the total gain. Tax is 20% on capital gains (above allowance) and between 7% and 38% for dividends above the allowance, depending on your income tax band.