The stereotype goes that the French are not as strict towards punctuality as the British. They have longer lunch breaks (up to two hours) and don’t always arrive on time at meetings. In the UK it is seen as very rude to be late to a meeting whereas in France it is indeed treated quite casually. Arriving five to ten minutes late is ok and they won’t apologise for doing so. So don’t be surprised and think they don’t care about the meeting.
On the contrary, if conversations become very passionate, the French won’t hesitate to stay a lot longer than planned. The same goes with working hours. Staying late at the office, until 6pm or 7pm, is quite common especially in more senior positions.
Don’t forget also to make appointments for both business and social situations. In France, you can’t just arrive at a house or a meeting unannounced as it is regarded as being extremely rude.