The rusty disc doesnt look too bad to me. Some cars, inc the Jazz, get surface rust on discs very quickly when not driven regularly. Even overnight in damp weather.
The body work adjacent to the inner wheel lining doesnt look great but I am more concerned about what you can see in the background. Looks like a brake line is badly rusted.(although this part of the picture is out of focus ) . Sometimes dubious 'cowboy' car dealers might seek to disguise this with a coat of paint, or worse still, a coat of underseal. This might deceive a buyer but not an MOT tester.
There also appears to be other rust in the same, distant ,underbody area but this is not always a bad thing. Some suspension parts are made of cast iron which is notoriously difficult to effectively prime and paint. Its often left unpainted and allowed to form surface rust which is actually quite an effective protective barrier on cast iron.
I'm surprised that Honda dealership is selling an 8 year old car direct to the public. They would normally pass it on through the trade. It could indicate that its a particularly good example - but maybe not.
I agree with the others. If it doesnt feel right, trust your instincts. I dont know the legal situation about return of deposit etc. The citizens advice bureaux might be able to advise.
