You can request a c-section even if it isn’t medically necessary. This is known as a ‘maternal request c-section’ or ‘planned elective c-section’. According to the guidance provided by the National Institute for Health and Care Excellence (NICE), your hospital should support your request for a c-section if they feel that you have made an informed choice. In other words, your doctor should listen to your reasons for requesting the c-section and can generally only refuse your request if they have a good reason (eg if the risk of likely harm from the c-section to you or your child outweighs the reasons for your request).
You can request a c-section at any time, including during labour. However, if you make a request during labour, you may have to wait if other individuals in your maternity ward need c-sections more urgently.
For more information, read the NHS guidance on caesarean sections.