Collecting tax on a UK web site

Hi all,

I’m selling in the UK, and am a sole trader. not vat registered. My business does not turn over a revenue above £85000 which is below UK threshold for registering tax. I’m currently building my website.

Therefore do I need to tick the box, collect taxes when selling an item. I imagine I do to the value of 20% or the item wont be sold with vat?

Do I also need to register for a VAT number with hmrc in order to tick the collect tax box on the shopify options. Sorry, struggling to understand collecting tax or not.

Thanks in advance all.