welcome along mate, wave goodbye to the holiday fund lol
from experience i would say dont bother with discs unless its needing them - none of the discs ive tried have been enough of an upgrade,save up and go straight to better calipers - sti brembo's are a good point. if you want to do something cost effective to them meantime try braided lines and mintex1144 pads,should get both for 100 quid and make a reasonable difference.
powerwise,exhaust system either full decat or sports cat, uprated plugs and fuel pump and a remap - Alastair at trackhound tunings getting good reviews and about 250 for a remap i believe
hope to see you at a meet somewhere soon
cheers Dave