Hi Qwert12345,
There is a facility on Gov.uk website where businesses can verify a UK vat number, it will show the address of the business:
Check a UK VAT number
Ordinarily we don't except a buisneses to use their agents address or PO Box's, you have to provide the address the business is trading from for VAT. We may except this under certain circumstances. you can explain this on your application as to why you wish to use this as your principal place of business (PPOB)
Thank you,