Can speak on behalf of Surrey. I did MEng Civil Engineering and the modules in the final year are from the MSc programmes in Bridge, Geotechnical, Civil, Water, Infrastructure, and Structural engineering. So there is a mix of UG and PG students in most modules.
There are many optional modules available however, there are ONLY four modules in the geotechnical engineering group which are compulsory for Geotechnical Engineering MSc. The modules do cover a lot however, and you take 8 modules in total (in this case four compulsory and then four optional from the disciplines above) and a dissertation (worth 4 modules = 60 credits).
Any more questions please ask.