Hi Shambles. Welcome aboard!
Tyre noise has been dealt with by my learned friends. As for seats and comfort, I would say that the Zed isn't particularly low or compromised comfort wise compared to most proper sports cars. The seats are OK but not great - I'm pretty average height and I get a bit achy after 200 miles or so.
The Zed's a pretty good GT but like Tim said, if you want to waft about you may be better in a second hand XK.