Due to the differences of formation and transformation processes of cities in Iraq and Britain, trying to adopt the same system of planning practices from one country to another is a real challenge. However, identifying the good models (concepts and practices) that can be re-applied on historic Iraqi cities needs to precisely consider the climatic conditions, socioeconomic influences, and physical properties of the urban form.
Here is a good paper adopted a comparative approach that studied British cities and Iranian cities (which culturally and environmentally close to Iraq).
Karimi, Kayvan. "The spatial logic of organic cities in Iran and the United Kingdom." Proc. Space Syntax 1st Intl. Sym. London. pp (1997): 1-17.
The first step is to increase knowledge of the experiences of developing and rehabilitating the historic English city centers and to introduce them to decision-makers in Iraq
Actually, I agree completely with your idea that we need to Know firstly the best practice in the original city (British cities) according to indicators we choose as well as the conditions environment after that we will be able to try to achieve it in Iraqi cities.