Also, you might want to try YouTube. the FIA GT Series and the Blancpain Endurance Championship broadcast all their races live on YouTube. The FIA GT Series is a pair of 1-hour races with a driver swap at the half-way mark (one on the Saturday, one on the Sunday). They have 2 rounds left this season, one at Navarra in Spain and one on a street circuit in Baku, Azerbaijan. The Blancpain Endurance Championship is a series of (usually) 3 hour races, although the Spa 24 hours and Nurburgring 1000km are standout longer events. It’s all GT3 cars raced by some of the most famous names in sportscar racing, ex multiple world rally champions, F1 drivers and Nissan GT Academy winners.
The European GT Open and European F3 Open also broadcast live on Youtube. Similar deal to above with the GT. A 70 min race on the Saturday, 50 mins on Sunday. Jan Magnussen and Gianni Morbidelli are amongst the regulars there. The Spa round was this weekend and the Sunday race was held on a drying track, brilliant to watch. And the Saturday race was on at lunchtime, which gave a great alternative to watching F1 qualifying.
I went to see both the GT Open and Blancpain when they visited Silverstone this year. Tickets were dirt cheap, it only took 5 minutes to get in the venue, the spectacle was great and the paddock was completely open. Great opportunities to get close to the cars, drivers and mechanics.