Games are usually on Friday and Sunday and sometimes on Tuesday as well. So it should be possible, to visit a game during that time.
Slavia has a very modern multifunctional arena they play in but the older Sparta stadium is also not bad.
O2 Arena - Slavia
Tesla Arena - Sparta
Tickets are on sale online for Slavia, use
o2arena.cz. Overview is czech, but after picking a game there, the booking works in english as well. Best seats available for CZK 260 / USD 14 this season.
Sparta offers only the possibility to order by phone or mail. All infos in english are
here. First category for CZK 195 / USD 10 there.
Long time to go until next October. But I'm sure, you will enjoy your days there.