Tracey,
Rules of thumb....
Insulin delivered by your pump acts for around 5 hours - that is, will have an effect on your BG for around 5 hours, most effect at around 2.5 hours but 5 hours nevertheless.
How long your carbs act for varies according to which food we are talking about and what else was taken at the same time. Active time from around 1 hour to 5 hours.
Biscuits are bobbins for use in a hypo situation - go for pure fruit juice, Lucozade or Jelly Babies - the latter being my personal favourite, 5g of fast acting glucose per 'baby'.
Breakfast cereals - the main ones - Cornflakes, Rice Krispies and the like peak (for me) at around 1.5 hours - big spike.
My only advice is to "read the book", don't panic and try to make rational decisions on what you have been taught by your pump providing folk. Test every hour or so but don't panic.
Have you got the bolus wizard set up? If so, you should be able to see the amount of "active" insulin in your system. My recommendation is that you set up the bolus wizard as soon as you feel competent to do so and be prepared to adjust settings as you get used to your pump.
Hope this is of some help - difficult via Forum posts really - nothing in real time. PM sent.
Alan