I've been in and out of school for a number of years, and I can understand perfectly the feelings you describe. I've gotten better, but I still sometimes freeze up when it comes time to write a paper, study, complete a reading, etc.

I think the first step is to recognize that the wish to avoid work and procrastinate is normal. Unless you're a mega type-A personality, just about everyone would rather sit on the couch and watch TV than write a paper or study for a test.

The problem, I think, is that when you feel like procrastinating, your anxiety kicks in automatically. You feel anxious because you feel lazy, and this forms a vicious feedback loop. That's how I view the problem, anyway.

The solution, I've found, is just to force yourself to sit down and do the work you need to do. If tea/coffee/whatever helps you do this, that's great. I've found that once I've broken through the "barrier" of anxiety, it goes away. And the more you do this, the easier it is to break the barrier.

Remember, everyone feels lazy when it comes to homework. Your stress over it is just amplified.