Are their any good tutorials on how to include functionality from a .el file such as https://github.com/dakra/datomic.el/blob/master/datomic.el my google searches are failing so far.

https://gist.github.com/TheBB/367096660b203952c162 looks promising

probably in my .spacemacs file

i'm suprised there isn't a convention. so i need to update my path to include a folder and put my lib there. I can't use .emacs because thats under source control. Though i guess a file could be gitignored.

If it's self contained code, then add it to the dotspacemacs/user-config section. Or create a private Spacemacs package containing the .el file.

Adding it to the user-config would mean copying the entire .el file into it?

Yes, its a lot of code too, so a private package would be the recommended approach

It doesn't look like it's a normal Emacs package, otherwise it could just be added via dotspacemacs/additional-packages in .spacemacs

https://develop.spacemacs.org/doc/DOCUMENTATION.html#managing-private-configuration-layers

thanks ill take a read, might be more trouble then its worth.