As has already been said, the LBF isn't really an author event and most publishing professionals are involved in meetings in the agents' centre, where all the rights selling (the heart of the event) goes on.
It's an interesting day out and most of the events are very good. I'm going this year: my agent has asked me to meet a few editors there (she's going to be trying to sell a book of mine there), and I've been asked to give a couple of interviews, which is nice. But it's not a social event, and I'm only going to be able to meet the people I'm meeting because my agent has set everything up. We have very strict appointments and will have to adhere to them.
Don't go there with a view to finding an agent or a publishing deal. The easiest way to find an agent is to send your work in to them, following their guidelines to the letter.
Yes, you can get one-to-one sessions at most writers' festivals now but very few agents go to these events; and even if you are asked to send your work in following those events, you will just end up in the slush pile with everyone else. So go to writers' conferences with a view to learning about writing and publishing, meeting people, and having a great time, but not in order to get representation.