Hi Jim and welcome to Bird Forum.
I’m not a birding expert, more of a nature lover who enjoys watching birds and learning, but I’ll try my best to help. I know there has been a Wryneck at Pleinmont recently (go south down the west coast of Guernsey as far as you can go (by car). See
This site shows you the reserves:
Click on the green dots!
La Claire Mare by the coast has a nice hide, but you can always see plenty of waders all along the west coast from Pleinmont northwards. The coastline here is flat and easily accessible and you can get nice close views of the birds. My favourite parts are the south end of Vazon (Richmond end, Fort Le Crocq) and the dunes at Vazon. Another good spot is Grandes Havres (further north), lots of Turnstones, Ringed Plovers, Sanderlings and others.
There is a thread by Malgos that you might like to look at - lower down on his page. He has visited Guernsey in the last week or so.
Good luck in Guernsey, hope you enjoy it.