A quick google search tells me the standard barbell is just a 22 pound bar. I don't know if this is true, but if it is, what's stopping you from working with it? You just have to add more plates to get up to a starting weight. If I'm wrong, everything I say after this should be disregarded.
I'd say if you cannot afford to switch gyms, go ahead and do the regular SL routine, replacing back squats with hack squats. From reading a shit ton about hack squats, I see that they are mostly used as assistance work, but it can still build your back squat numbers. Your quads are still going to get work, as is your butt, the only problem will be your abs and back will have a small lack of practice stabilizing heavy weight. There is no reason to not work your legs if you have the means to do so, and if it's either "do nothing" or "do something", then do something.
If money is the issue, I strongly reccomend saving to move to another gym. Some probably offer Christmas / New Year specials, where if you buy a one-month membership you get one free or something. So if money is the issue, save up and wait for one of those to roll around. When you get to where you can do full squats, drop the weight of your hack squat by 10-20% and start full squatting, paying extra careful attention to form.
I honestly do not see a problem in working with a "standard" barbell and replacing squats with hack squats until you can get to another gym. But it's important to get somewhere that has an olympic barbell and a squat rack.
And do you go to a college / university? If so, don't they usually have a gym you can workout at for free, equipped with most of the standard equipment? I know that the schools here do (UK and Transy), but I don't know about others. Anyway, look at other options for sure. But do something rather than nothing; SL / SS > Something > Nothing.
bout to get torn up, i can feel it.
quick edit: seriously look for another gym