Ok,
So I've given the car a reasonable run over the last few days through some corners that I know it understeers on more than others, and I am surprised at the difference literally swapping the round has done. I wouldn't say the car is transformed, but I am much more happy with the way it behaves, seems to have much better turn in, and better exit than it used to because I'm assuming that even though the rear has the crappy tyres on now, because the weight shifts to the rear it sticks anyway and because of the front tyres being more grippy, they hold on better too!
Thanks for the help people!
Matty