I have had bad stomach cramps since 29/7/13, and I am due on my period next week. My cramps can last from a few minutes to about 10-15 minutes, I generally get these in the morning, sometimes tea time (5ish) and bedtime, I'm worried that I might be pregnant :/ is this a possibility?

No, does not sound like pregnancy, sounds like you are going to have a bad period, this is a sign of a period.

There are almost no signs before you miss a period. You have to wait and see if you miss a period, if you do, it has to be two weeks late to test