Methotrexate and Imuran/AZA both primarily reduce the activity of B cells (a kind of white blood cell).
The biologics (Remicade, Humira, Cimzia) primarily affect T cells.
Some people respond well to one, some to the other and some need both kinds. And of course sometimes people respond differently to 2 different drugs even though the drugs do pretty much the same thing.
If you responded really well to MTX then it may make sense to switch to Imuran. However it takes up to 4 months to figure out if Imuran works for you.
You could bridge this time by taking something like Entocort but alcohol can increase side effects like dizziness.
You may be fine on Remicade or Humira and there are no warnings about
interactions with alcohol for them.
If you are going to drink to excess (more than 2 drinks a day) then you need to realize that you are risking much more than the other people around you. Mainly you are taking a chance on damaging your liver badly. Because you have Crohn's you are at higher risk of problems with your liver to begin with. There are very few symptoms of liver damage until the damage is very advanced. So it's hard to tell when you're making yourself sick.
You really can't live without a liver
so it would be good if you could keep this in mind when you start drinking so you can take steps to stay in control.
Alcoholic drinks of all kinds stimulate the intestines and may make symptoms like diarrhea and cramping worse. Drinks high in sugar are worse than ones that don't have much sugar (i.e. carbohydrates).
What is your doctor recommending? I assume your doctor understands that you want to be able to drink socially. If not, I would make sure he does.