Johnno, In your case I think the 8" would be OK if you add a trolley with blow up wheels to your list of accessories. This will let you carry it outside easily without shaking it up too much. You are lucky not to have to go outside your backyard for a dark site
As for the planets and DSOs, yes the 8" f6 GS scope is a great general purpose scope for all of these objects. I use mine most clear nights on everything from the moon to galaxies with great results.