The number 7 bus goes straight to the RSCH from right outside the front entrance to Brighton station.
Frequency? Every 7 minutes :shrug:
Getting there by car? It'd be a damn sight easier getting dropped off at the RSCH than it would be at the Amex :shrug:
Agree its not a brilliantly situated site, but if your 'serious injury' doesn't prevent you 'trek[king] up that hill' or getting 'dropped off by car' then it probably wouldn't prevent you from catching a bus or a cab up there either