I don't think you want a credit card. They become an addiction (I know all about debt addiction). How about a bank overdraft? Honestly, think about your gift choices though.
Ipads are so expensive, I'm sure she'd appreciate something at half the price :)
Edit:
Overdraft is when you agree with your bank, you can basically spend (for example) £200 more than you actually have and then pay it back when your account is next credited with your salary or however you get money. This will normally be subject to a small monthly usage fee and interest (usually small) and you will need a debit card to withdraw money from the ATM or make online purchases etc. A debit card is just what you use to gain access to funds in your bank account.
This is what you should do, tomorrow, go to your bank and ask them about getting an overdraft. However, if you have a current account you might need to upgrade your account which usually is subject to an additional monthly fee. For example, my bank account costs a total of £140 per year to own. Something like that.