The general rule on breaks is that you are entitled to a break of 15 minutes after a 4 ½ hour work period. After a 6-hour work period you are entitled to a break of 30 minutes, which can include the first 15-minute break. There is no entitlement to be paid during these breaks and they are not considered part of working time.
If you are working 9 to 4.30 you would generally get a 10 or 15 min morning tea break. You may or may not get paid for this. In some offices they would expect you to take this tea break at your desk, particularly if you get paid for it. The half hour lunch break (unpaid) is standard.
I worked as trainee accountant for a number of years. In general I would work 9 to 5.30 with morning tea break at my desk and a half hour unpaid lunch break. Earnings were not much more than the minimum wage too.