I think you should give him a chance but NOT wait. He must take that chance now. I agree that you're making an important distinction when you say he'd only go to counselling 'for me' rather than 'because he acknowledges he has a problem'.
Taking responsibility is the issue here. And yes, at some point your boyfriend will need to stand up and say: 'I'm an alcoholic' - and mean it. Indeed, this will be his first step on the road to recovery. That all said, I am encouraged by your boyfriend's willingness to seek initial help, even if it is purely to appease you. It suggests that at some level he wants to please you and keep you on side, misguided though he may think you are in your appraisal of his condition. A lot of alcoholics in denial over their condition will refuse outright to discuss their drinking, and they'd rather eat the glass their whiskey is served in than hold a frank discussion with a shrink. So I do see hope in your predicament. But I am concerned that you might let this situation drift and maybe even deteriorate further before you insist your boyfriend gets the help he needs.
If he's going on two-day binges, his need for help is urgent. Please set up that appointment with a counsellor ASAP, or else contact Alcoholics Anonymous for further advice (tel: 01904-644026 or: www.alcoholics-anonymous.org.uk).
If things go badly, however, and your man doesn't play ball with the counsellor, or refuses to acknowledge his addiction, please don't allow the situation to continue, rolling from one crises to the next. You're not helping his addiction by playing the role of the worried, passive carer. In fact, by 'indulging' his self-destructive behaviour this way, you might even be fuelling it. Sometimes it's only through 'tough love' that the people we care for can be jolted out of bad behavioural patterns. Tough love is often practised by withdrawing the sort of support that's intended to help but is ultimately allowing the loved one's bad habits to flourish.
In your case it might involve leaving your boyfriend in the hope that it would help him come to grips with his condition and seek sobriety.
First you'd need to tell him what you expect from him - what level of partying you regard as acceptable; what hour of the night you'd like him home; what kind of state you expect to find him in when he walks through the bedroom door, etcetera. You'd present your requirements as an ultimatum. Then, if he disappointed you, you'd walk. It might be the push he needed to admit to himself that his life was a mess.