Old English looks like Welsh and Icelandic combined. And yet it looks a bit like German.
Speaking of Welsh and Icelandic, double L, "ll" makes the same sound in both these languages and is unlike anything in present day English. It is a voiceless lateral fricative (Ll - Wikipedia). According to one Icelandic pronunciation video, this sound is made by placing one's tongue to one side of the mouth and blowing. It works for me.
Watch this video to hear the sound.