Gary is it on all the time, or just intermittant?
If intermittant (might still be worth a look if it's on all the time

) then have a look at the wiring connector from the TPS.
It goes into a loom with the wiring from (IIRC) the MAP sensor (or is it the MAT one?), but the important thing is that the plugs may loose the 'good' connection over time (or through being disturbed).
If the connectors seem okay, follow the earth wire (have fun, it goes all over the place and is hidden inside a plastic sleve) but ends up under the coolant expansion tank, where it attaches to the coil base plate.
This is the connection which caused my problem, as it should have a plastic spacer/washer thingy to prevent touching chassis earth when bolted up - if this is displaced you will get a wrong earth reading and fault code 22.
If this doesn't work, are you going to Donington?
If you can get the car there, i have a 'spare' TPS which i can bring along - it isn't for sale, as such, but if it cures your problem, then you will know what you need to buy, and i am happy to loan it out whilst you get a replacement - if it doesn't then i'm out of ideas
