A goalscoring striker and a next level up right winger have to be top of the list. Maybe a decent left back if one is available.
Maybe easier said than done, but as you say, there must be fringe players in league 1 or 2 or youngsters in the Championship or Premier League who need game time.
The loan market should open up more options.
If we don't act and get a bit more quality in, we aren't going to make the play offs.