I think they are likely to take into account reasons that you would not go through with the plan. If you had no reason to live, no thoughts to stop you, then that would be more risky, but as you said, you would not want to do that to your mum. As long as that remains a protective thing within your thoughts, I do not think they would automatically decide that you need to be an inpatient.

But if you trust your T, I would just be really truthful. Your T is going to have your best interests at heart.

Take care.