Dorran Constructed Homes

Without considerably more information it is really impossible to answer your uery

I googled Dorran Homes and AI gave me this
Dorran homes are a type of post-war prefabricated housing built in the UK between 1947 and the 1960s. Constructed from precast reinforced concrete (PRC) panels, they are known for structural issues like concrete degradation and steel tie corrosion, which often make them unmortgageable through standard lenders.

They seem to have been built mainly in Scotland. having found the data you did not give us, I would say the answer is relatively simple

AI tells me; you should find a suitable experienced survey
To find a surveyor who understands Dorman homes (like Dorman Long or Dorman prefabricated steel-framed houses), you need a Structural Engineer or Chartered Building Surveyor with expertise in non-traditional construction and system-built properties. Because these homes often contain specific structural or cladding issues, generalized surveyors are not always sufficient.

Again AI tells me

How to find to Find the Right Surveyor
1. Search Specialized RICS (Royal Institute of Chartered Surveyors) Directories. Many surveyors specialize in pre-fabricated or non-standard construction methods (like BISF, Dorman Long, etc.). You can locate these specialists via the RICS Firms Register. When reaching out, filter for Residential Surveys and specifically ask if they have handled Dorman Long or steel-framed non-traditional properties.

2. Seek Independent, Structural Engineers
If you suspect significant issues with the steel framework, you may need a Chartered Structural Engineer rather than just a Building Surveyor. You can find structural engineers experienced with historic and non-standard steel frames in your area on the Institution of Structural Engineers Directory.

Both these directories are available online.