Part M is for guidance. Does this mean sections of it can be ignored if it suits me to not do it? Specifically section 5.5 says unisex wheelchair accessible toilets should not be used for baby changing. This is a new build, building other than dwelling.
Guidance, when used in the context of Building Regulations, does not mean that they are optional - rather the Approved Documents provide guidance to building control, who will interpret them to determine whether or not your project is compliant.
In this instance you seem to be referring to Part M: Volume 2, which applies only to buildings other than dwellings. If your planning permission is for a dwelling, you do not need to adhere to Volume 2 of Part M. See page 2 of Volume 1 for more information: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/540330/BR_PDF_AD_M1_2015_with_2016_amendments_V3.pdf
Andrew (Build It's digital assistant editor)