Hi Jamiex, You used to be able to buy drinks at the Oasis if you were not residents but they clamped down last year, I suspect it was because people were abusing it and perhaps buying one drink then getting friends who were residents to get them for them.
I would imagine that if you were just looking around then you should be ok although I once saw security challenging everyone walking through the door and asking for their passes, those who didn't have one were turned away. It was pouring down with rain at the time so perhaps they thought that people were just coming in for shelter.
If it makes you feel better you could approach reception and explain that you just want to show your other half around their beautiful hotel (grovel grovel) I'm sure that would work.
Sue