Hi John,
Fixed rate ISAs work if you can afford to lock your money away for a period of time. If you need quick access to the cash as an emergency fund, the interest rate you earn is negligible. However, if you want to make money from your savings and can afford to put it aside for at least five years, it might suit you better to spread your investments across your ISA as well as an equities ISA and/or stock investments.
Interest rates are so poor right now – and set to be horrendous for some time – that you may find investing your spare capital is more likely to return more on your investment than leaving it in a savings account!
(**Not financial advice, please seek professional advice before making investments**)