Hi mkcchan,
Thank you for your further question.
The rental income received from the car park space would still fall within the residential ruling.
However, due to the fact that the guidance previously supplied came from the Stamp Duty Land Tax Manual we are unable to give you a definite answer to your question within this general income from property forum.
We would suggest that you contact HMRC seperately for full clarification.
Self Assessment: general enquiries
Thank you.