Thank you both for your input. I have found it odd for the architect to suggest this. Especially when the permission has been granted and there have been no clauses for the bat survey.
Direct quote from my architect:
“ I have been talking to the RBWM borough ecologist today on another project, who has confirmed that when roofs are being taken off all planning applications will now definitely need a bat survey, so we will need to carry this out”…
The original permitted development application was to change the chalet bungalow (has two floors) into a traditional house design, but I have since decided to add to the porch, and convert what will be the new loft into a store room and play room. My logic would say that no bat survey was mentioned previously by the local authority so it would be best to avoid this for the application of the additional work!