I've been to Gleasons & it is a proper boxing gym, not part of some national/global chain.
I'm sure that they'd let you trail it.
It won't have a staff of personnel trainers & pretty receptionists though.
I used to train at Gleasons before it moved, it's got good boxing equipment and usually lot's of pro's training in there. It's a good gym if you don't mind looking after yourself and using the bags and stuff...
The personal training was quite expensive when I went there but I think they might have some classes in the evening when you can join in otherwise it was just turn up and amuse yourself!!
I don't have that dedication anymore and found it hard to keep going