Hi Louise,
I had quite low temps (just off the chart and I made the chart!) also at the beginning. Most women will fall within the bounds of the chart, but not necessarily. It may have to do with the time you take your temp, I was taking mine quite early, and so I just adjusted the chart to suit me. I found that after a while as my periods settled down I crept up to within the usual range. Also it's very common to get one temp that's quite low or quite high depending on your activity levels, diet etc. Ideally when you chart you want to start at the first day of your cycle, which is the first day you come on, so you can get a picture of the whole cycle when you reach the first day of your next period you mark it on the chart you're finishing and then again on your new chart for the next month.
Hope that helps
Maria