Generally speaking, my undestanding is that:
UK domiciles who are ordinarily resident in the UK are taxed on their worldwide income and worldwide capital gains. Trading proceeds ought to be treated as capital gains I believe.
There are always offshore companies, trusts, alter egos in the caymen, etc .... which have the intension of hiding gains or income from the UK tax man. But this is essentially tax evasion, and generally not advisable. There are always clever accountants and lawyers who offer to set you up all sorts of difficult-to-trace paper trails to hide your proceeds, but if the chips were to ever come down, you alone are culpable.
You always have the option of living outside the UK for 6 months+ per tax year, and you are only taxed on UK-sourced income and CGT. Pick up a pad in Paris, maybe another in Amsterdam, dust off the old backpack, and you and your laptop could be tax-exempt nomad!