Depending on the size of a recruitment fair and who will be there, you may be able to find somebody there representing a company you want to work for. It might be a bit of a sneaky way of getting your foot in the door of a company, but with the right angle you can engage in a good conversation with somebody who is representing that company; it’s probably a good idea that you find out what they do first before wasting your time on somebody who can’t get you in the door and where you want to be.
If they are of a high enough level to get you a good job that you want to do in that company, you may want to use your social skills to your advantage then share your vision and passion with them; let them know what you can bring to the company, and how that will benefit them. Use your advantage to schedule an informal meeting with them over coffee for example and use your angle to get what you need; this could be something like “I have a lot of good ideas, and I would like to brainstorm with you, how about we schedule an informal face-to-face meeting over coffee to discuss this further?”
For those of us who are have lots of confidence and natural social ability this one can be a winner with the right angle and approach; you have nothing to lose by trying.