You are right, both are a great addition, Ashes before FG, crucible just gives a "grinding" playmode, but for cheap money quite ok.Loyalist Packs just add fancy stuff, though the wisp is a very nice to look at pet ;)

You can still start playing and enjoy the game without the addons, Ashes extends the main story and FG gives a "side story".

Just note that Forgotten Gods requires you to have the Ashes expansion so if you can only afford one in the sale get Ashes first.

You can certainly have a lot of fun with the base game and your characters will carry over when you do get the expansion/s.

Thank you.