Anyone know some reliable sites around Sidmouth, Devon for Common Hawker & Golden-ringed Dragonfly? (And any other species I can't see in Norfolk!)
I'll happily reciprocate gen for anyone visiting Norfolk!
I don't tend to go as far east as Sidmouth when I'm in Devon, and my preferred site for those two specific species would be Prewley Moor, which is the wrong side of Okehampton from your point of view so not much help.
You're close to Bystock Pools, a Devon Wildlife Trust site, which is good for dragons and is reported to have golden-ringed although I didn't find them when I visited. It's reliable for small red damsel which will probably be of interest. Look for the path across the valley, which includes a boardwalk across the "long ponds".
Also worth trying Aylesbeare Common, which is good for various dragonfly species and should give you a decent chance of common hawker.
NB not claiming that these are the best sites, or even the nearest - just the ones I happen to know.