can you lose money investing £3000 in an isa?

[ssd]

is it based on the stock market and can your investment of £3000 go up as well as down? the interest rate on the isa is 3%

is it a cash ISA or a stocks and shares ISA?

Cash Isa, can't lose money, won't gain much. If based on stock market can go up or down.

If it's quoting a 3% interest rate chances are it's a cash ISA. So you can't lose the £3k you put in, but as the rate of inflation is currently 3.1% your money will be depreciating slightly in real terms (ie in terms of what it can buy).