i believe bonnet pins are not road legal. they look extremely ricey too
if your only doing once a month private trackdays, there isn't much point for an extinguisher or a CAMS license. bare street trim with perhaps an oil cooler, oil sump baffle, surge tank and maybe a bigger front mount will be fine imho. (this is of course on a stock GTR)
what i also suggest is a dedicated set of brake pads and track wheels and tyres. r specs would be nice, perhaps a set of Falken Azenis (cheaper) or Dunlop DJ01's?
most importantly, don't over do it. keep it simple, 1 warm up lap, 3 or 4 hot laps depending on your pads, tyres and other equipment and then 1 or 2 warm down laps for each session.
ps. dont pull your handbrake up in the garage area after a session