Well, you could wait it out about a week in primary, the same for secondary, given the ingrediants, or just roll some dice and go with those numbers. Serously, a hydrometer is a REAL good investment. It saves on buying new bottles after you've used the old ones for grenades.
From a couple clues, I'm guessing a U.K. brewer? You have gotta get to a homebrew store, not the local grocery place. Invest in some equipment, and you'll be happier with the end product, trust me.