There's no investment or savings account that will guarantee keeping pace with inflation. Look for building societies that pay decent interest rates, eg Coventry or Leeds.
As nannynick says, you need an emergency fund of money that you can access easily. Instant access accounts have poor interest rates - I think NS&I's Direct Saver is paying 0.5% which is a decent rate by today's standards. Is that the account you have already?
You could put some of your money in a fixed rate account (either an ISA or a bond account) as they have higher interest rates, which are fixed for the duration of the account. You have to leave the money in for a fixed time period (usually counted in years, eg either 1, 2, 3 etc years , and the interest rates are higher the longer the duration of the fixed term). With a fixed rate bond you can't access the money before the maturity date (apart from if you die). With an ISA they have to allow you access to the money but they put a penalty on it, eg loss of interest on the amount you withdraw. At the moment the interest paid on fixed rate bonds is higher than on ISAs. For example, with Coventry Building Society a 1-year (actually slightly longer) bond pays 1.2% but an ISA pays 1.05%.
www.coventrybuildingsociety.co.uk/member/savings/fixed-rates.html
If you're able to save some money every month you could also look at a Regular Saving account. These let you put in an amount each month (limited to a maximum amount per month) and pay a higher rate than an instant saving account. The account usually lasts for 12 months (or 24 months in the case of Leeds Building Society) after which the account matures and your money is moved to an instant access account (paying very low interest), but you can stay alert and find a higher paying account to move it to.
Coventry is paying 1.05% (the account lasts 12 months, maximum £500 per month) and Leeds is paying 1% (account lasts 24 months, maximum £250 per month). Rates aren't fixed so might change during the course of the account.
www.coventrybuildingsociety.co.uk/member/product/savings/regular_saver/regular-saver-5.html
www.leedsbuildingsociety.co.uk/savings/regular-saver/regular-saver/