Hi The Will! I think you may as well wait and purchase Stormblood if you get Heavansward combined with it. Your going to have to complete 140 story quests which will take you a week of solid play to get through before you can start Stormblood. I came back to the game roughly 2 weeks ago at the same point you are now and have churned through nearly the first 90 quests. However this is playing a couple hours a night as I work! What I can tell you is that the story is really good this time so if you needed something to play for the next month before stormblood it might be worth picking up cheap. Regardless of your choice it will be money well spent and remember you've got like 2 years to get through stormblood as that's how often the expansions come along! Good luck with whatever you choose!