If you're looking for a 'rainy day' fund the basic rule of thumb is to put aside 3 months salary. That's just for emergencies, breakdowns or repairs.
This could be a good opportunity for you to take control of your money. Draw up an personal budget report. It's basically a list of your income and everything you spend money on. They're really useful if you find yourself in debt, but they're also a good way of finding out how honest you're being with yourself about those 'little treats'.
The most useful format is from the Money Advice Trust:
Money Advice Trust Budget Form
The first time you draw it up you'll find you spend much more than you earn, but it does help.
If you're looking for advice about specific products I'd recommend surfing through the forums at
Money Saving Expert. The contributors are ordinary folks who are friendly and willing to share their experiences.
Good luck.