For the record, before the rain on Friday 1st October I found the cave (Lathkill Resurgence Cave / Pudding Springs) at the base of the tufa dam to be bone dry. I got in on the Saturday, even after 22mm of rain and took some pics, though the water was only a short distance away upstream.
After the rain on Sunday 3rd the river started to flow, and by afternoon on Monday 4th was running all the way to Bubble Springs. Home Grove risings were still dry. During the following week the river retreated right back to a point above Bateman's Shaft, though Home Grove was flowing slightly, and Lathkill Resurgence Cave was still under water. So levels are dropping quickly. Don't give up just yet!