i have been looking at up and down transformers.....really confused as to which one i need to purchase
Step-up and step-down in this context refer to what the transformer is going to do with supply voltage, i.e.
step-up transformer = Lower voltage in, higher voltage out;
step-down transformer = Higher voltage in, lower voltage out.
So to run 120V equipment on the U.K.'s 240V power supply, you need a step-
down transformer.
It should say, or at least mine says: Input 100-240v. That will probably cover most of everywhere in the world, if not everywhere.
Just about everywhere. Japan & a couple of other far eastern countries are 100V, a few places in Africa, the middle east and the Indian sub-continent are 250V, and practically everywhere else is either 120-127V or 220-240V.