I don't know exectly what's going on in Olympic football/soccer, but I do know that in virtually every team sport, there are pre-Olympic tournaments to narrow the field of contending teams to a managemable number. There can only be so many teams at the Olympics, because there are only so many days (18 or 19?) during which a tournament or round-robin competition must be completed.

Futbol/soccer/association-football is already at the max ~ their Olympic tournament actually began a day or two before the opening ceremonies. There's no way a greater number of teams could be accommodated than those curretnly selected.

WV may have a point: whereas the separate English, Scots, Welch, and Ulster teams apparently all fell short of qualifying for the Olympic competition, a combined UK team might very well have made the cut.