Yep ........ was going to recommend rescue remedy when I first saw your post but I thought people would give me grief for suggesting such a thing and I also thought I wouldn't want to get somone in the 'habit' of taking it all the time !! Took it once many years ago before my wedding (as did my best man ;-)) and also before my first solo x-country. All back in the 90's - never taken it since, but it does calm you down yet you still retain sobriety !! Still got the bottle somewhere ........
Other than that I was going to suggest talking with your instructor but you've already touched upon that one !!
I do know where you are coming from with regard to failing and then having to spend more money etc etc. It only adds to the whole fear thing, but try not to get too wound up. When my IRT arrived it was one of the best flights I ever did but whilst taxxing I tried to respond to a call from TWR on the radio call using a yoke mounted A/P switch instead of the PTT switch - til the examiner pointed brought it to my attention !!! Ha !! That's subliminal nerves for you !!
Good luck.
CG