You might want to re-think this strategy. As long as you pay your credit card each month it will cost little or nothing, maybe $50-75/year for card membership. At least in the states, there are cards that will pay you back for using the card between 1 - 2.5%, sometimes even higher for special offers. This is competitive with or even better than most savings accounts and does not tie-up your capital.

The danger with debit cards is that if a merchant makes a mistake or commits fraud, that money is GONE from your account. You have to fight to get your money back, and in the meantime may incur overdraft or insufficient funds penalties if the cash to cover legitimate transactions isn't in your account. In my experience, the banks are difficult to deal with regarding these disputes, and worse, have no qualms about seizing funds from any other accounts to cover the shortage in your disputed account. By the time you get the dispute resolved and the cash credited back to your account, you may have racked up several hundred dollars in overdraft and returned transaction fees from your bank and other payees that had your payments returned, which can take months to resolve.

Add to this the fact that security is so lacking in the ACH system used for debit transactions that it is amazing that fraud isn't more widespread. Basically any ACH-approved merchant, or person who opens an account with an ACH processor, can access your funds without a password, PIN code, signature, or any other proof of your authorization. All they need is your debit card number and expiration, or bank routing number and account number.

Personally, the only places I use a debit card are in my bank's ATM's. For everything else I use cash or credit, and just pay the credit cards off as soon as the bill arrives.