When should I apply for VAT and tax for my UK-based online store?

[Davidnock]

Alright a guys. So Iv just finished my store and it’s now live. I just want to know when I should apply for VAT and tax. I’m from the Uk and will possibly be selling internationally. 

[Pickle_Rooms]

I may or may not be a chartered accountant....but ain't taking no liability with a blog reply!