Horlick's Malted Milk Tablets are still available online at the Vermont Country Store (vermontcountrystore.com, I think?). They have them in chocolate. You can get a package of 4 boxes, each box has 3 packets, and each packet has 8 or 9 tablets. They still taste great.
And on the subject of floats and sodas, I've heard them called both, and they involve (in Michigan, anyway) pop (root beer, coke, vernors, etc.) and a scoop of ice cream plopped in. I can still remember going to the Vernor's factory in Detroit on a tour, and we got all the floats we wanted... took me years to want one again!
And last but not least, malted milk shakes... are available all the time at Big Boy restaurants, where they make them thick or thin (to your preference), in usually chocolate, strawberry, and vanilla, and they serve it with the metal cup beside... oh, heaven.
Better late than never, but I got here by searching for malted milk tablets, so I imagine someone else will. Hope this helps!