We adopted Charlie last week, and indoors he is an absolute darling

However, there is one thing we need to work on, (and I think he may have been allowed to practise this - he's about 5- so I know there isn't a quick fix).
He isn't offlead yet, and when he sees birds /planes, he really, really wants to chase. Because he can't he shrieks / barks, and basically goes way above 'threshold' / can't hear you. When in the garden he scans the sky , but we have had some improvement with me calling him back, and then rewarding him for doing something I ask him to.
We made some mistakes with Boysie in the early days (completely different 'issues')

, and don't want to do the same with Charlie , so I thought I would set out what we think we could do, to get some feedback as to whether it is on the right track, or what else we should consider.
I know he should not be allowed to practise this behaviour, so we will be trying to avoid wide open spaces where he can see huge groups of birds. But he needs to be walked, and we will probably be unable to avoid birds completely.....
I have a copy of Control Unleashed, and was wondering whether we should work through the exercises, or concentrate mainly on 'Look at That'? Inside he is the most chilled and relaxed boy

so not sure that the Relaxation Protocol is worth doing?
Any feedback / input / ideas gratefully received !
Thank you