The correct reply to this is: consult a duly qualified financial adviser (which I am not).

My personal opinion (which is not financial advice) is that 6 months is not long enough to invest; you probably have little option but to keep it in a savings account (or more than one). Based on the recent failure of several banks, choose one that you trust rather than going for the highest rate of interest at the possible expense of security.

If you plan to save enough to put you over the £50,000 mark, read up on the Financial Services Compensation Scheme before you do and consider using more than one institution.