Price your ipad in UK and ask if they are part of the VAT back scheme (blue global I think). if so then ask at the time of buying for the process forms to be completed.

You must purchase within 3 months of moving abroad and you present the item, receipt and forms to HM customs VAT refund desk at the departure airport and they will arrange a refund to your UK bank account. There is a fee which will be deducted when the forms are filled in but its definately worth it, I've just bought a decent camera and done this.