When working A/G I use 'roger' in reply to almost every aircraft transmission of intention or position report that requires no other response, at busy times I'll add the call sign. I use 'Out' after broadcast transmissions, for example reporting a change in QNH/QFE. 'Over' is the only one I don't ever use.
We get a lot of 'request taxi' and other such invalid transmissions related to communications specific to other types of facility. Not a complaint simply an observation.
Departue A/G - initial contact:
"Goodchap Radio, G-ABCD request radio check and airfield information" and "G-ABCD ready for departure".
Arrival A/G - initial contact:
"Goodchap Radio, G-ABCD at Location request airfield information".
The CAA released a supplement to CAP413 including audio of the radio calls used for each type of ATS being used. I have this found very handy -
http://www.caa.co.uk/docs/33/CAP413Supplement.pdf
In moments of thoughtlessness, high workload or stress my comms when flying have been pretty awful so no stones will ever be thrown in this glass house.