Just to report back:
Couldn't quite stretch to four new Goodyears or Michelins but got a good deal on four new Yokohama BluEarth AE50s at the wider size of 225/45 on the same 17" rims.
Grip is much improved, lateral grip is huge (but this just down to having some half decent rubber on there) bumps are softened and dulled down, less crashy. Its still jittery and I feel everything, so some new dampers are next on the list.
Sadly I may have to sell it, I'm expecting our first child and I can barely fit a pot plant through the gap between the seat and the B-pillar let alone a small human!
With four new injectors, a new MAF, new spark plugs, new stat and four new tyres this car is so much more improved though.