Trust me this is not worth it at all. If you want to have fun, you will have alot more of that if you just use occasional, stick to using on weekends only, or at least 2 days in a row max then 1 week break. This should keep it worth doing for quite some time without tolerance killing all the fun. I don't really know how bad codeine withdrawal would be for you, but for me who has been addicted to opiates before, the whole idea makes me cringe. Using for a month in a row (or whatever it takes to get addicted for a beginner, I don't remember, it may possibly take longer) will result in you getting much less out of your opiate and on top of that you get all the negative aspects of using at the same time. One month (if it will even last that long before tolerance kills the fun) on a pretty weak opiate that will probably lose alot of it's charm quite fast, and then to endure withdrawal after that, is just not worth it. Keep in mind also tolerance can be a bitch to deal with once it sets in, even if you would prolong dependance by taking weeks off, having to endure weeks of semi-withdrawal while thinking of opiates all the time (trust me you will) is just as bad as going through withdrawls themselves. I advise you to reconsider this. Codeine has a ceiling dosage also, I suspect incoming posts in the next month about what the next stronger opiate will be if you go decide to go through with this.
Edit: You can always find sources etc, it's really not something that stands in your way and is of benefit. I only had access to codeine/tramadol at first, that did not stop me from seeking out buprenorphine and after that heroin/morphine when all the fun effects from the latter had started to fade. These days, anyone can get drugs anywhere with a bit of patience and a computer. I will not say how though, but it's easy to find out. It's easy to tell yourself you won't do this, but once addiction sets in, it can make it feel like it doesn't really matter anymore. For me it did, already addicted to opiates moving up the food chain was not a hard decision. What difference did it make, I was still going to stop, just one more hit™
I did stop eventually, but it took 7 years longer than expected.