Will i be able to drink alcohol once a fortnight while on paroxetine?

Yes, but moderately!: Since alcohol increases the effects (AND side effects) of paroxetine, you really should be very moderate in the amount and strength of what you choose to drink. That is certainly not too frequent, but do keep the drinks weak (low in alcohol content) and few. Do have a pleasant time but take care. It's not bad advice for people even w/o the medication issue. Best wishes!