Actually, it's true that with a card you use as a debit card in ATM's, you can go into a bank and withdraw a higher amount. However, even though it is your cash and it is in the bank, they will charge you cash advance fees. You are probably better off just taking money out of the ATM every day for seven days.
My father just did this when he was here. The ATM was not accepting his card, so we went into the bank and they processed it. However, he was charged cash advance fees. He uses Sky Bank and when he called them the following Monday they told him they had had a freeze on all UK ATM withdrawals (no idea why) for a few days...
The next day and the rest of the trip he was able to use the ATM with no problems.
Banks are strange places.