That's a shame, fresh mozzarella is fantastic. You can make a decent pizza without it but, personally, I wouldn't bother with the plastic mozzarella and just use something else.
If you do manage to get hold of some try a tomato and basil salad with the mozzarella torn up in it, tis yummy.
I'm sure this is debatable, but there is a reasonable substitute for fresh mozzarella if it's unavailable. Whole milk ricotta, right out of the tub. You can get that stuff at almost any supermarket, and most of it is of generally good quality/flavor. It's pretty similar, usually made from the leftovers in the mozzarella process, so you have finer grains of curd and it's not stretchy. The important part is that it contains some of the same liquid. But it's really good on a pizza.