Sea Lion Press has, since 2015, been devoted to publishing alternate history. Named after the hopeless would-be German invasion of Britain in 1940, they have an extensive amount of published works.
And now, Sea Lion Press has embarked on an ambitious expansion, aiming to be, in their own words, “a crucible of activity in the counterfactual fiction world.” This includes articles (starting with one about their namesake), and a forum.
It’s well worth a shot. I’ve read some Sea Lion Press works and wish them the best of luck.