If a VAT registered person buys goods from another EU country, supplies his VAT number and has them exported to Ireland, they should be sold VAT free... in theory anyway. I say in theory because I have come across companies in the UK who refuse even though they are obliged to.
If you turn up in person I think you will be charged the VAT as the goods have not been exported. You would be free to reclaim the VAT off the English Crown Revenue service but only if you also supply goods and services into the UK. I rang them to ask about this and that's what they told me.
Cheers
Joe