After getting the car and washing it...
...I did the first mod which was a remap.
It took as a while to find the ECU but after a bit of digging we got to it.
The result was 210bhp and 420nm from the stock 177bhp and 350nm.
The new map is quite conservative as we didn't want to push the high mileage turbo too much. It's still a big improvement to stock and the car pulls like a train thanks to the torque. No downshifts needed for overtakes!