In addition to what Craig already shared above, the thing is that the dates of the semi-finals are only decided on Easter Sunday by lottery, so you still have to wait until then to know with a certainty what weekend the semi-finals are being played.... and then, yes, find someone local who can go buy tickets for you once they go on sale.
This year, tickets were being sold only about 4 DAYS before the matches!!
Nothing is a given, you might be here and still not get a chance to go see the matches. If you're okay with the uncertainty, you can come and be lucky to get tickets standing room in the sections reserved for one or the other team.