I have a cash ISA, the interest rate is higher then a standard Savings account, and you can access it at anytime, but can only put £3600 in one year. Personally i put the cost of monthly car insurance and house contantents insurance monthly, then when i get the renewall pay each item of in full saving me the interest rate the car insurance company's add.
Got alittle fund building up due to the interest gained over time if i hit the £3600 limit (remember ISA's are tax free Savings account are not) then id have to think weather to and start Stocks and ashares ISA which has another £3600 limit again tax free and has no garrentee of making any money as there depentant on the stock market-