I have dual citizenship between the UK and US
I am currently living in the UK, and am a student at university. So I don't pay tax.
I would like to open a trading account to invest in either UK or US stocks. How does the tax work for me?
If I only invest in UK stocks (is that easier than investing in US stocks from here?) do I have to pay tax to the US?

And, I am graduating next year and plan to move to the states then, if I keep my UK citizenship how will tax work then, from the US?

Thanks :)

SInce you are a U.S. citizen, you ARE liable for capital gains taxes on the trading account. The fact that you are investing only in UK staocks is irrelevant.

I cannot answer for sure about the U.K. taxes, but, generally, European countries do NOT tax their citizens on income earned OUTSIDE of the U.K.