Yes you are... excellent choice. I have one
The C-Class made between 2004 and 2006 (aka post-facelift W203) are very well built and have very few issues.
The C180K has the 1.8L Supercharged M271 engine, which produces 143 BHP and is reasonably frugal.
There are a couple of common issues, mainly that these engines need new timing gear at around 100k miles, but if allowed to fail the timing gear can cause serious engine damage and it is therfore best replaced preemptively at around 89-90k miles.
There is also a potential issue with split vacuum hose under the air box which will cause loss of power, and oil leak from the front camshaft position sensors. If you check these two points, you should be fine.
On my own 2006 C-Class however none of the above went wrong, and in its 9 years of faithful service the car only had a couple of minor electrical issues which were easily fixed.
So in short - comfortable, refined, and reliable - highly recommended.