VAT start

I registered for VAT. My date is 1st May. Could you advise how to prepare my account for this big day. Where to start and what should I focus on.
100 per cent of goods I import from Poland. I understand I should collect 0% VAT invoices from my suppliers, but when should I pay UK rates.
Part of the goods are 0% in UK (kids boots) - I sell mainly on Amazon(on 5 EU marketplaces) and I created Clients separately for each country. Should I create more clients for each country and for each Vat rate?
I do not even know what to ask:)

Cannot give specific business advice with out looking into things in detail, either you need to register for vat or not in first place if you have what would be best scheme BUT now you have vat registered , Do you know which kind of scheme you have gone for? Mainly you have to charge vat on items not subject to zero%

I did not choose any scheme. I will make Vat returns every 3 months. But I think I have to search google and will be back with my questions after( I don’t want to repeat stupid questions:) Thank you Faraday.