Yes, it is a pain.
We now fly from Glasgow or Edinburgh to London on a flex ticket (even when we booked reward flights), and then stay the night at LHR (and have a night out in London). Last time, the Premier Inn cost £24.50 (and the cocktails in Soho were £14 each!).
Flex means, on the way back, we book one flight - with good time for connection - and then can move it forward or back if need be. And our insurance kicks in after a three hour delay anyway, regardless of EU261 or weather.