I paid a deposit on a pick up of 4800, 3180 of this is vat, how do i record this transaction?

Forget about recording the VAT until you receive the VAT invoice (that's the document that says what VAT you have or have not paid).

VAT Invoice will show £15,900 plus £3,180 of VAT = £19,080

At the moment, you've simply made a downpayment of £4,800 on that £19,080 - so just record it as that (a payment/cheque to a supplier, Category = Accounts Payable or Creditors & NO VAT).

The deposit should now show as a credit amount against the supplier.

When you receive the invoice, enter it before entering the final payment & use the credit amount.

Alternatively (probably simpler), enter a dummy invoice from the supplier then enter the payment as you would a normal bill payment.

Once you receive the actual invoice, you can edit the dummy as required.