On average, how many hours a week do you work?

[Chatham Lady]

I'm contracted to work 37.5 hours per week plus one hour day for lunch (unpaid).  However due to certain monthly deadlines I often work an extra 30 minutes or hour to get things done which make one week out of four to be 40 hours.  Alternatively, I take a quick lunch so I can get out on time or when my bosses are in as they're often out 3-4 days a week.