Recommendations please

I'm trying to make an end grain cutting board. This is my practice project, so I'm trying to keep costs as low as I can, but I have still spent about $300 on woodworking tools so far :'( so I need to make this work to justify not going to Etsy and getting a fancy ass cutting board.

Onto the problem - I'm using poplar dowels (I know not the best wood, but I wanted to practice) for the board, and after the first glue up I realised it's not completely even. I have a japanese block plane but I can't make it work for the life of me. I tried to chisel away some of the higher pieces, but I can't control it well enough to be precise. How do I make it completely flat before I cut the pieces and glue it again? Would an orbital sander work? I debated getting an electric planer but I don't want to drop another $100 right now.

Any help is appreciated. Thank you :')

I'm trying to make an end grain cutting board. This is my practice project, so I'm trying to keep costs as low as I can, but I have still spent about $300 on woodworking tools so far :'( so I need to make this work to justify not going to Etsy and getting a fancy ass cutting board.

Onto the problem - I'm using poplar dowels (I know not the best wood, but I wanted to practice) for the board, and after the first glue up I realised it's not completely even. I have a japanese block plane but I can't make it work for the life of me. I tried to chisel away some of the higher pieces, but I can't control it well enough to be precise. How do I make it completely flat before I cut the pieces and glue it again? Would an orbital sander work? I debated getting an electric planer but I don't want to drop another $100 right now.

Any help is appreciated. Thank you :')