My colonoscopy escort cancelled. Does booking a taxi solve the problem?

My friend texted, "I can book you a taxi, but I can't take the afternoon off." She had agreed to collect me after a colonoscopy and stay with me that evening.

My hospital letter says I need a responsible adult for the arrangement I have been given. I am planning to discuss sedation with the unit. [NHS advice says someone needs to collect a person who has had sedation, and they cannot drive for 24 hours](https://www.nhs.uk/tests-and-treatments/colonoscopy/what-happens-on-the-day/).

I have not started the preparation yet. The appointment is next week, and changing it would mean rearranging leave and the person covering my shift. I am tempted to say the taxi is sorted and hope the unit accepts it, but the driver has not agreed to be an escort or stay afterwards.

What should I ask the unit before I look for another person or another date? I want to solve the actual requirement, rather than arrive with a transport booking that answers only half the question.