For handling, I would get some rear locking pineapples. If you can afford it, some lower springs ARBs and good alignment would come in handy. Obviously decent tyres help, even with its very tailhappy in the wet. Oil cooler definatly for sustained high speed runs, if your running more then 12psi I would recomend a front mount intercooler, much higher and get the fueling checked out, maybe a jez chip for fuel economy benefits. Oil temp guage wont be needed with an oil cooler IMO. Prob best to keep the stock rims to make the car look cheap, some nice matt black spray will also make it look less then 1K.
Brakes, if your going to do anything sustained on track on the journey, new discs and some ferodo ds2500 or at least some mintex (no where near as good but half the price. Obviously some new fluid. Check the clutch is in good order if your planning to do fast starts running more then 260bhp the standard kit might not be up to it. Also you can remove the clutch damper to make the clutch more controllable and easier to bleed.
http://www.zeroyon.com/index/content/view/32/47/
post in the wanted section and bump for anyitems you want if no one has ads for 2nd hand kit.
Check engine thoughly too