For more meetings (well at least 3 for nearly every rider) Reintroduce the (Berger/Mirror) Grand Prix Series from the late 70's. Find a National Sponsor.
15 tracks, 84 riders - open to anyone who rides in UK. Each track has one meeting with 16 riders. So, 72 riders will get 3 meetings and the 12 lowest ranked riders will only get in 2 meetings. Riders who currently double up in Prem & Champ can get one meeting at each 'home' track. Keep local fans interested.
After 15 rounds, top 16 cumulative points scorers make a Grand Final. The winner could be the Wild Card at the British GP. And in addition the top 16 British Riders in the series qualify for a British Final. You don't ride in UK, you don't make the British Final. Start the series early in the season, so that the finals can be raced before October.