Thanks for that. According to Clause 5.1 you can indeed ask employees to work additional hours as and when needed, although it should only be in exceptional circumstances, rather than it becoming a regular thing. To be honest, we as lawyers, almost always have such clauses included as we never know when a case may come up which needs additional work and it is quite common for lawyers to work overnight and over the weekend, particularly in the corporate sector when a deadline for a transaction is looming.
We do not get paid overtime for that and your contract also says that no overtime is due so no extra pay is required. In fact, the law does not provide for automatic overtime pay and it will only happen if it is mentioned in the contract. However, you must ensure that based on the hours she has worked for the month and the pay that she received, she has received at least the minimum wage on average.
As to Clause 5.2, that relates to working more than an average of 48 hours a week, which is the legal limit. This clause serves to remove that limit, meaning that she could potentially be asked to work more than an average of 48 hours a week. However, it is her legal right to opt back into this limit and get that clause removed so you have to agree to it if that is what she wants and cannot penalise her for it. Do not that this won’t remove the rights under Clause 5.1 and she can still be asked to come in and work extra hours if needed, for no pay, as long as on average that does not result in her working more than 48h a week on average.
Does this answer your query?