If you can wait for one of the occasional offers, you can do better than a 63-64 plate at the top end of your budget, before options. After deducting what came with offer at the time, I effectively paid a bit under 20 for a 2016 PP. Admittedly not with what you want, but there's only two of those I'd be remotely interested in.
DSG - Not for me, even if the manual is bang ordinary. I hope it is a lot better than cooking equivalents. However, it would seem to work better with ACC.
PP - Got that, though not entirely convinced yet.
Sunroof - There for free ok, otherwise not remotely fussed.
Dynaudio - Would like to have had that, as someone who doesn't really go down the aftermarket route.
PP/ACC/Xenons all std if you buy the right car by the sounds of it.
Fuel consumption is as always a mix of the car, the circumstances and the driving style. I do something around 50% motorway, 25% normal roads and 25% 5mph crawl and am getting near to 36mpg. However, that is driving with a bit of realism & some advanced knowledge - I managed a fair bit more than the supposed norm in my last car as well, even if not in mid to high 30's territory.
Mods/tuning - Not my thing as I'm from the want a faster car, buy one from the off school. Unless expensively done for the sleeper POV.