Well coming from someone that is diagnosed as a rapid cycling bipolar II I can tell you that they will start you with an almost standard set of meds if you turn out to be bipolar I or II.
First off you will be offered Lamotrigine or Lithium for stabilizing your mood swings. If you are on the more depressed side they will probably want to try Lamotrigine first. It has less side effects than Lithium, the downside to it is that 5-10% of people will develop a rash from it which can be fatal (1 in 50000 people that get the rash get the fatal kind - think skin falling off) but if the rash is caught in time they have medication that can fix it. Every day you will have to check your whole body for a rash, EVERY DAY, after about 8 weeks on it the chances of getting a rash from it are pretty much nil, you should still check every day though. Lithium can be even more annoying because you will probably have to go get a blood test done every 2 weeks or so that way they can check the levels in your blood to make sure you are in the therapeutic range. Too little it doesn't work, and took much isn't good for your body.
If you have a tendency to slide into the mania side of things they will probably get you on Epival which will help curb the mania before it gets out of control. If you do end up manic they will most likely put you on seroquel or olanzapine, both are anti-psychotics and will help bring you back to reality if you have gone manic.
A lot of people that are bipolar almost always have some other form of mental illness as well, the most common is some sort of anxiety disorder. This is why a lot of people that are bipolar get misdiagnosed as major depressive, prescribed antidepressants, and then the SSRI/SNRI pushes them into full blown mania (that's what happened to me) and they finally get the proper treatment. Also, if you are having a hard time sleeping they will probably put you on a Z-drug like Zopiclone.
To be honest it doesn't sound like you are bipolar though. Mood swings, lack of concentration, sleeping problems can be symptoms of a lot of disorders; ADHD is the first one that comes to mind or it could simply be that there is something wrong in your life that needs to be adjusted rather than the chemicals in your brain. If you find yourself so depressed that you don't even want to get out of bed, and then for no reason all of a sudden one day you feel like you own the world and nothing can stop for a couple of weeks and then you are depressed again then it's probably bipolar. If you just have random mood swings for no reason that last for a few hours, can concentrate and have problems sleeping it's a very good chance that you have something like ADHD or just plain old clinical depression.
So don't let them rail road you into thinking you are bipolar if you are not. There is a big trend in some places like the USA where every shrink thinks everyone is bipolar and are more than happy to start pumping you full of drugs that won't help you at all. My personal opinion when it comes to shrinks is if they prescribe me anything on the first visit they aren't worth my time. After your doctor gets a greater sense of your problems then he should start prescribing things.
To me it would be like going to your family doctor with a stomach ache and having him tell you that you need major surgery before even examining you.
Have a long talk with your doctor, explain everything you feel. What I would suggest is keeping a mood/sleep journal. Every time you have a mood swing right down the time and how bad it was and when it comes to sleep record the time you go to bed, and in the morning write down how long you slept (or a rough idea) and how well. When it comes to the anxiety write down every time you feel it build up and where and what is going on around you.
If you go to see your doctor with that info it will be a lot easier for them to figure out what is going on with you.
Hope that helps, and I hope you are not bipolar, it's something you have to deal with the rest of your life and even on meds its sometimes hard to keep on top of it.