Hello Paul,
as Andy says, you have an excellent set up for carrying out CCD observations of variables. For several years, I used a 100 mm refractor for doing just that. I know from the quality of your CCD images you have posted that you are well placed to pursue variable star work if you wish.
Do have a look at the info on the VSS web site (there is a PDF document “The New Variable Star Section CCD Target List” at http://www.britastro.org/vss/VSS_CCD_Target_list2_20110401.pdf if you are looking for targets).
Good luck and let us know how you get on.
All the best,
Jeremy