Hi, I have pre-reg exam 2 weeks today so i've been trying to swot up on as many areas as possible :S
Knowledge comes with experience from when you graduate. After seeing things that you are taught in theory in practice it really drums it into you in various scenarios. When you're not having various bits of interesting but useless information forced into you, you're more able to absorb the bits whihc are applicable to practice.
ie. One of the main modules i did last year was "production and characterisation of comericaaly important drugs". I haven't seen a single UV/IV spectra since then and haven't had to interpret a mass spectra either
Try not to worry about it and learn as much from your experiences as you can, people won't expect you to know it all already.