Thanks all.
Bill, for this sort of work, depending on the surfaces, a 'glue' is not always a good thing. Super glue can be used for fixing in order to hold an item in place, but generally, I use a 'cement', as in poly cement (tube/liquid/ etc) to provide the chemical reaction bonding of the surfaces. Any 'glue', even 2-part epoxy etc can, by its very nature, break the bond at some time, whereas a cement has literally welded the parts. And of course, poly cement, in it's various forms. can be used in a controlled fashion, allowing a clean joint without blemishes, although may need minor clean-up when set.
As for sanding - it's a case of delicate 'finger feel' and experience!