[356graham]

You've got a little over a week before the track day. If you go with exchanging your cores for rebuilt, you should have plenty time to get it done. Removing and replacing calipers is much faster than cleaning and rebuilding the calipers. Sorry, I don't know of a shop in Europe that provides that core exchange for rebuilt service.

Check your rotors to see if they are within spec. You need to measure the thickness of the rotor and check for uneven wear. It is possible that they are ugly, but don't need to be replaced. If you can't check or question whether needed - replace. Still not a hard job.

Check your rubber lines also.

You can get this job done in a week provided you have access to the necessary parts.

Don't rush, however. These *are* after all the most important safety item on your car.