The best thing you can do is brew the style of beers that your temps allow you to. Unless you want to spend the money to get something that can control down to lager temps, I wouldn't brew any lagers. At best, you're going to spend a lot of time and effort fighting temps only to get an end product that is probably far from what you are expecting from the style.
Like colbalt said, you're probably better off just getting a clean fermenting ale yeast that is suitable for the temps you will be able to achieve and likely end up with a far better tasting product compared to trying to force a true lager.
Temperature is one of the single most important aspects of brewing good beer consistently. Don't try to fight it and work with what you have, or spend the time and money to build something that will create the environment you need for a particular beer.