In Australia, the most readily available substitutes for Future are Pledge" One Go" and Pascoe's "Long Life". Both of these products are available "off the shelf" at your local Coles/Woolworths/Safeway supermarkets. They are similar, but not quite the same as the original Future.
Both contain cleaning agents, and Pascoes will dissolve Tamiya acrylics. It failed the "drip" test over Tamiya acrylic, so it never went anywhere near my models. One Go works fine as a clear parts dip but when airbrushed over a model, it doesn't seem to give the high gloss that Future is famous for.
Moving up a little, Bunnings stock a number of products which may be viable alternatives, but I've not tried them. Two which I have seen on the shelf ate "Floorshine" by Feast Watson and "Gemini Floor Sealer Finish" by Peerless Pro. Again, all I know of these products is that they state that they are acrylic based floor coatings - I've note tried them at all.