Join your patient participation group. The NHS is under tremendous strain, especially with GP numbers decreasing and our expectations increasing. Her majesty's government seem to think that just by saying things like "we will have GP cover 7 days a week" will mean it will happen, prepare yourselves for a big surprise, it isn't going to happen.
I also think that any problems with our care should be discussed with the care giver in a formal manner, in writing. Discussing our woes on a forum achieves very little except for highlighting how widespread these issues are.
I will defend our NHS to my last breath, warts and all. We don't want the sort of system they have in the US.
Seriously, join your patient participation group, it will help in understanding the sorts of problems that running a surgery involves and will also help in conveying your own issues with the way things are run.