I discovered that I can buy cream cheese at 1/4 the price per pound, but only if I buy it as a solid 10 cm x 10 cm x 40 cm brick. Assuming I only eat 1/10th of this brick per week, is there any way I can store it so it does not go moldy in the meantime?
The "best before" date is usually way out. Cut it in slices that you will use within a week. Still Tasty recommends that you use opened, refrigerated cream cheese within a couple of weeks. Very well packed (well wrapped or preferably vacuum packed) cream cheese really should last longer than that. I'd try for keeping a month's worth, refrigerated, in well wrapped packages that you won't open until the last one is gone. Freeze the rest. Frozen, it will lose some creaminess, but will still be good in cooked applications. Again, Still Tasty is a bit (IMO) overly conservative. They suggest (for quality only, not safety), keeping opened cream cheese in the freezer for only two months. I'd allow at least three, if not four. Of course it will stay safe in the freezer indefinitely. In the fridge, just watch for mold, toss the whole thing if it develops mold. You can't just cut off the moldy parts like you can on hard cheese.
EDIT: Just FYI, some places in the US that sell the 48 ounce brick also sell 50 count, 1 ounce packages. Quite a deal for less than $2 more, epecially if the sell-by date is well out. (This picture is from Sam's Club, but I think the other big warehouse store carries the small packs too.)
I suggest freezing it in oil (so that ice crystals do not form), according to the following procedure:
Acquire a sealable plastic container, such as Tupperware, just a bit larger than the total amount of space (volume) the stored cheese will occupy. Obviously you're not limited to the configuration you described. But this method will preserve the cheese for several months in an airtight environment.
Place the whole block of cheese in the refrigerator and leave it there long enough for it to come down to refrigerator temps; this will make it easier to cut it without deforming it, leaving you nice clean little bricks to work with and enjoy.
Place a medium-size bottle of vegetable oil in the freezer, and leave it there long enough for it to come down to freezer temps. Vegetable oil cannot freeze in a typical household freezer. Also add the container you'll be using to store the bricks of cheese in.
Separately, prepare sheets of wax paper, the dimensions of which are the same size as the broad side of each individual brick of cheese, (whatever size you choose), plus of course just a slight amount of overlap (especially on one end). Refrigerate them too, that and one large sheet for your work surface. If you own stone plates of any sort, (a pizza stone will do just fine), go ahead and refrigerate one of those as well (or freeze it if there's room for it). The general principle is to keep everything down below room temperature as much as possible. So once you get started with the cutting process your aim is to work as quickly though safely as possible.
Temporarily remove the block of cheese from the refrigerator, just long enough to remove it from its wrapper and score it along its top side, making marks wherever you intend to cut it. Place it right back in the frig.
For cutting you will need an ample supply of unwaxed dental floss, a long thin-bladed knife (carving knife), a small kitchen brush (flat and broad), and a shallow bowl of refrigerated vegetable oil. Set up your work surface with these items about the perimeter. You'll also want a bar towel to clean the knife off with as you work.
Place your refrigerated stone plate onto your work surface, Cover it with that large sheet of refrigerated wax paper. Place your opened oil container (the one you'll be storing the bricks in) to your right or left (depending on which hand you are). Brush a thin layer of oil uniformly over the center of the wax paper, covering an area just larger than that of the block of cheese.
Wasting no time, remove the block of cheese from the frig and place it on the stone plate. Brush oil over the top of the entire block of cheese, and pour a little oil into the storage container (meaning the oil from the freezer).
Oil an appropriate length of dental floss, and use it to cut your first slice. Just wrap ends of the floss around your hands/fingers and pull real tight for this, forming a length of string only slightly longer than the cheese is wide. Don't saw. Just go straight down though the soft cheese. Still, it won't go all the way through (along the middle of its course). So brush more oil into the new gap, oil you carving knife, and gently use it to complete the process. Allow the brick of cheese to fall over into your hand and onto the little piece of wax paper you made for it (them), and press it (rub it) on. Immediately lower the brick into the oil container with the paper side down, and add enough oil to now submerge that brick.
Quickly repeat this process for each brick of cheese. Then cap the container and place it back in the freezer. Any time you want to replenish your supply you'll simply have to remove it from the container, drain it, and then wrap it for a little while in a high quality paper towel. Now transfer it to whatever you normally keep your cream cheese in.