Poecile palustris
Glossy black hood and plain, pale brown upperparts. Cheeks brownish towards nape. Small, rounded, black bib. Small pale spot on base of upper mandible (often surprisingly visible, despite small size). Very similar to Willow Tit, especially British sub.sp. Willow tit has bigger head, not so glossy cap, whiter cheeks, larger bib and pale wing panel.
Wikipedia: map (se also Xeno-canto below)
Birdlife ecology