I was interested to see this thread as I have exactly the same symptoms. The judder is not always present, but when it's there it's always under light acceleration at 1500rpm & just over 20mph.

So what is the conclusion ? It looked like it was the valve body right up until the TC was mentioned.

I also seem to have very slight slippage when cruising on the motorway. With cruise control set at (say) 70 mph the rev counter appears to move up and down very very slightly, maybe ±25 rpm, even though the road speed is constant. It is more apparent going uphill. I'm not getting any errors from the TC but I think the juddering and the slippage could both be consistent with the TC not locking properly.

I'd be happy dropping the pan and inspecting the valve body myself, but that means new fluid and I'd probably be better off putting that money towards getting a new TC fitted as that will also mean new fluid, properly flushed too.