Thank you all.
You see, I don't mind the presenting itself I don't think, I probably wouldn't like the questioning bits though. It's the travelling there when I'm 33 weeks pregnant (I'll have to fly) and the costs (I'll have to cover everything!).
@Tt_dan - I think it depends on the conference set up. It may be different in other areas but in my experience, you can have 1) main presentation where you're presenting to everyone there (so hundreds of people), 2) paper presentations, where there'll be a few going on at the same time (so probably dozens of people, pending on your topic and interest of others) and 3) poster presentations where there'll be even less people. Mine is only for a poster presentation so I think it's 5 mins presentation, 5 minutes for questions. As for the numbers, in my case, not many...
Re: prestigious, it's not huge but within that field, I'd say it's big enough. Maybe it's worth bearing in mind that this is not in my field, but a related field and I have no plans of staying in academia so networking may not be the best either.