The advantage of a recruiter is you can be much more honest with them. Their goal is to sell you into a job - that's how they get paid - so they genuinely want to find something that you will accept and that you will be good at. Whereas when you interview for 1 specific role you're more focused on trying to sell yourself into *that* role, rather than selling yourself as a candidate in general.
It's fine to say "My goal is FT work but I'm happy doing temp or contract even part-time until the right opportunity comes up". Just don't go in there and say "I'll do anything, either FT, PT, whatever!" As that can reek of desperation. And I say that because it's one of my own main frustrations as a recruiter - after all, if I don't know what they really want, how can I help them? Likewise, if there's something you really don't want to do (such as a particular company or type of role), then be open about that. Just don't come on too strong or too negative in any particular thing. Let the interviewer drive the process - they'll have set questions they want to get through. But they'll also want you to ask questions and be interactive.
My number one interview advice is to be honest and open, and relax. After all, there is nothing to lose. Good luck!