When you come to the UK you'll need to register with HMRC as a sole trader and you'll then declare your earning via a self-assessment tax return each year.
You'll be taxed on the profit you make from your business activities (income less expenses) regardless of where the income is generated from. You are correct that VAT isn't required, that only comes into play if your income was to exceed £85k.
Regards
Taxevo - Specialist Freelancer Accountants
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