Two birds I'd like help IDing - one is possible chiff chaff - other is a kestrel, possible juvenile? Many thanks

Hi! 

Both seen recently in Yorkshire. I'm guessing the first (in my garden ) is some kind of warbler, but would appreciate it anyone can be more specific. I also spotted the cutest kestrel and would love to know if it's juvenile male, or just an adult male fluffed up in the cold (and how to know).

Any ideas hugely appreciated.

Many thanks