A contract of employment is a legal agreement between the employer and the employee. It contains terms, either express or implied, which you cannot lawfully change or vary without your employer's further agreement.
If you wish to change some of the terms you should discuss the matter with your employer, perhaps with the help of a trade union representative. Your employer must (especially in relation to requests to work flexibly in order to care for relatives, and to take time off to study/ train) listen to and genuinely consider your request.
There is generally no legal obligation on your employer to agree to vary the terms. However, an important exception to this relates to the treatment of disabled workers. In particular, disabled employees are entitled to have reasonable adjustments made for them so that they can carry out their work – for example, changes to hours and the provision of special equipment.
If you cannot reach agreement but must have the amendment to your contract, you can give notice to your employer and make the change unilaterally. This is of course a high risk strategy as the employer may reject the change and respond by lawfully dismissing you.
