Definitely put ?7,000 (the maximum allowed in any tax year) into an ISA. That doesn't define the type of investment, though, it just puts it into a tax shelter - you've still got to decide what to do with it. My choice would be a unit trust from one of the top performing companies such as Fidelity. You have to think of this a long term investment, though - after a year you might only just be keeping pace with a savings account, but after 5 you should be way ahead. What to do with the other ?3,000 depends on how much of your total assets this represents - if it is all of it, then you should consider balancing the risk by putting it into a guaranteed interest savings account. If you've got a few million more, then you could be more speculative with it, and invest that in a unit trust too.
Or you could ask someone who knows what he's talking about, such as a financial advisor. Mine doesn't charge me anything, he gets his commission from the investment companies.
*remember the value of your investments and the income from them can go down as well as up. Taking any advice from me could well lose you all your money.