Tax Implications on trading Eminis

Can anyone tell me:

As a UK citizen what the tax implications are for trading Eminis, namely the S&P500 and Russell 2000?

Do I pay US tax or UK tax, Both or none at all?

UK unfortunately, unless you want to experience the chancellors wrath and set up an offshore company

So how much do I have to pay?

What tax is it called, Capital Gains TAx? or something else?

Since the overwhelming majority of new E-Mini traders lose money it's only going to affect you if you are in the minority.

My understanding is that unless you are considered to be running a business (i.e. subject to income tax and N.I.) it's only capital gains tax - both on any "trading profits" and from any "profit" on on US$ margin funds when you convert them back to £ (if the £ were to have dropped during the period your funds were held as $) - with of course the annual CGT allowance.

So for 1 or 2 lot beginner traders it's unlikely to be an issue.

At what stage does the Inland Revenue decide one is running a trading business?

Are there any benefits to it?

I am a uk citizen and trade 200 eminis per day.

Really appreciate any info.