I've driven it again and I'm not so sure now.
For a start the pedals were being limited by the mat. D'oh! Why can't Peugeot bring the price of mats down just a bit from the hideous £70/set they charge now, so people can afford mats that fit?
So I shifted the mat and.... It still felt low. The accelerator does have a fair bit of travel on it now though so I can hear the engine grunt. Unfortunately my initial diagnosis of "there's no turbo!" still stands. Couldn't even spin the wheels in 1st on a wet road! It's slow but liveable under 40, but 70 comes up in approximately a week and it won't go much higher than that!

I'm hoping it'll turn out to be something trivial like a vacuum pipe or something. Ideas?
The clutch is the worrying thing though. I pulled the pedal and it's spring up a couple of inches! The thing is there's no resistance on those inches other than the spring on the pedal

I can push the pedal down to where the clutch actually starts with just the back of my little finger! If 406s didn't have such high bite points, it'd be undriveable. What the heck could cause this to happen, and how can it be fixed?
<steve_earwig> I think this forum is more about keeping our cars going with minimal outlay than giving our cars more reason to go bang