I don't live in NI so I don't know the exact way the law works
My guess is that massage might be a little safer, but you could still get into trouble
We do have similar laws in the South and so far only one punter has been convicted, it looks like the police in the South are not really targeting punters, this could change of course
In general, I think if you only see independent escorts and avoid brothels you will be ok
There is a small town close to me, and on the main street there is a flat being used by escorts, plenty of the locals know about this, so you can be sure the Guards know too, but so far it hasn't been shut down, maybe it will be soon