This would be amazing...
So you'd send BTC to the cards wallet and you could purchase anything in ££ as long as it doesn't exceed the current value of your BTC? On top of that, a credit card where you can pay off your credit in BTC?

You know, if there were no fees (e.g. 2.5% fee to exchange BTC to GBP for each purchase or something silly like that), and it could be used at an ATM like a debit card with no fees, I'd use this all the time, everyday.

Would the card have 2 balances (e.g. BTC and GBP) so that you can deposit BTC and exchange for GBP (on the card) and vice versa using the web/app? Or will it simply be a case of deposit BTC to make purchases / use ATM's and it is only exchanged for GBP at the current rate there and then, when you make the purchase?