Graeme, what adapters you need really depends on what you are trying to adapt to. You mention tracking scopes, e.g. SCT's. Scopestuff in the US has inexpensive adapters for all sorts of OTA's.
www.scopestuff.com 
For example in my case with the LX90 I ordered the following items from Scopestuff.
#TASS - SCT T-adapter for Direct Photography, Short (collar ring type)
#TTCE - Camera to T-thread Ring for Canon EOS