We have seen choughs in Anglesey, Pembrokeshire and Cornwall.
We’ve seen ravens round here, but they are not that common. I wouldn’t suggest here for a wildlife trip though.
As pp have said, look up RSPB reserves.
We go on wild life trips especially to North Norfolk coast (for birds), Pembrokeshire, Cornwall and the West coast of Scotland. We go to Oban, looking for white tailed eagles, golden eagles and sea otters - especially on the Isle of Mull. I assume there’s red squirrels there too. We do go to other reserves like Martinmere, Minsmere, Slimbridge, Formby (although the red squirrels there might have been hit by the pox?), Longshaw estate, Rainham marshes, Donna Nook, Framlingham marshes and any others, featured on Springwatch, etc.
If you want to see dolphins, Cardigan bay is a good place. We saw them off Pembrokeshire.