Hmm, like you said, it isn't set...
45 minutes should be more than 1000 words of quality, I think.
Everyone does paragraphing differently - I tend to have shorter than longer paragraphs, myself.
With an Egyptian period question, you've probably got around 5-8 main ideas, with a similar amount of paragraphs.
If you're doing a generic question, eg 'Evaluate x pharaoh', you'd do something like:
- Opening -> what defines a good pharaoh?
- military and foreign relations,
- religion,
- building and services for population,
- bureaucracy and government,
- women,
- image and legacy, conclusion.
That essay could probably be done with a band 6 in 1100, I think.
The more important things are first, so that if you find you're running out of time, you can just skip over them. It's important to have an even one or two line conclusion, though, regardless of how late you are.