$10K in eight months. How should I invest it?

I'm a 20 year old British student and will have around £8K ($10K) by this time next year. I will be investing it until I need the money in, at the latest, around 6 years.<br><br>I currently invest in:<br>- Stocks and Shares ISA ($8K, 40% FTSE 100 Index, 30% S and P 500 Index, 30% Euro Stoxx 50 Index)<br>- Fixed 5 year student bank account ($1.5K)<br>- Premium Bonds (~$1.5K at 1% interest)<br><br>Where should I invest the extra $10K? I don't mind 2-3 years of a high risk investment strategy if it increases the gains, but I would prefer lower risk. I am happy for the investment to be locked for 2-3 years.<br><br>The options I'm considering are:<br>- A 3 year fixed savings account (~2.5% interest)<br>- A 2-3 year savings bond with 3% interest<br>- Investing in money market funds (the only one I could find was around 2.2% interest)<br>- Adding the money to my Stocks and Shares ISA <br><br>What do you suggest?