I am looking for tools to improve my Colemak typing.

There are many good typing tutors out there, my favourite online is Typing Club. Unfortunately Typing Club does not help you with the Colemak keyboard layout. Of course you could use Typing Club but practicing with the DF adn JK keys makes no sense when not on a QWERTY keyboard.

Looking for typing tutor for Colemak was not straight forward but I did find TIPP10. TIPP10 appears very functional with lots of options, including a Colemak keybpard and event allows you to create your own lessons. The Colemak Website lists Colemak lessons that can be copied and pasted into TIPP10.

TIPP10 with Colemak layout
TIPP10 even shows a very handy Colemak layout