I think Spice and Wolf uses quite difficult grammar at times (at least in the prologue - did not check for the rest), so you might have a really hard time following the story if you don’t have a solid grammar foundation yet.
But what I can suggest is for you to check out the Absolute Beginner and Beginner Book Clubs! They read manga and also books, and you can read all the past picks, make use of their language dicussion threads and vocab sheets, and you can even ask questions yourself, as usually a bunch of people from the reading club still stick around and will get back to you, I’m pretty sure. Once you mastered a few books from the Beginner Club, you could move on to the Intermediate Club, depending on how you feel about their picks. Often the books in the Intermediate club are not dramatically harder, it’s just that the club’s reading pace was faster, but that shouldn’t bother you if you read after the club is finished already.
There is also the Master List of Book Clubs which contains links to all book clubs and other reading groups.
Happy reading!