Unfortunately no,
I’m 100% certain I’ve just done something wrong:

I’ve tried both the standard Subversion checkout URL from Github and tried appending it to link to the project file itself. It seems to recognise that the folder exists at the very least.
The documentation for UE4 so far seems to mostly talk about Perforce.
To be specific I’m new to this so I’m sure what I’m doing is wrong, in detail:
I’ve created a Github project repository to share the project with my friend. We can both commit through the Github desktop client independantly, but as far as I’m aware it checks out the project file so we can’t work together. I then use the Subversion Checkout URL Github has in the “Repository” line in the Source Control dialog. In the Source Control settings I can specify to use Subversion, I don’t have Subversions tools installed so I’m not sure if this is a necessity.
Is this wrong?