I have no idea why there isn't a decent agency in Belfast, there's a huge gap for it.
Well depending on your point of view I suspect a great many of us would struggle to describe any such operation as 'decent' in the true sense of the world, but assuming in this context that the OP means people who at least have a crack at proper security screening, won't take more than 25-30% of the money that she is earning and won't blackmail her/put her at risk/expect her to have sex with them for free, then as ever any names need to be kept for PMs. Although all the posts so far tell me is that the women in Belfast have more sense.
Of course I mean "decent" as far as that can be applied to the term "agency,"
and as exactly as you've described it (no blackmail, screening, etc). Tbh I know working with an agency is very unbalanced, in terms of who does most of the work for what pay they take home, but even now as a busy indie, I still think about signing up with an agency sometimes, just because of the learning difficulties I have and how they impede my organisation and memory. I'm constantly stressed thinking about if I've done something that will ruin my reputation, like forgotten a booking! I'm beyond post-it notes and alerts unfortunately. Would probs change my mind about that though sharpish if they let me see a dogdey client though!
Since it's sorta on the subject, I'd like to point out to the OP that there is no shame in wanting to work for an agency, whatever your reasons, and you've laid yours out. I always think "someone could get the impression from this forum that not going indie makes you inferior in some aspect" because we're all so passionate about being liberated and fully paid women so we always go "Blehhhh, NO." at the mention of agencies, but if it's what you want, it's what you want.
If you've got the skills to run your own shindig, I'd say go for it because I do think that if you can go indie and do it well, the pros of it outweight the pros of an agency. As Amy has alluded to, agencies don't give amazing support (and you're after support) as much as they'd have you believe (welcome to skepticsville...). All of this aside, in Belfast indie really is the only option you have to my knowledge, for outcalls anyway. I'll be so surprised if someone suggests an agency to you, none exists as far as I'm aware.