As Walls seem to use Tags, I'm trying to work out if a given block is a wall (e.g Cobblestone Wall), does anyone know a good way to go about doing this?

Thank you!

 

you can check if the Block you have is Block.COBBLESTONE_WALL
using the == operator

For a more generic check I guess you could check 

if(Block instanceof WallBlock)

or you could grab the minecraft WALLS tags and check if the block is in the tags

public static final Tag.Named<Block> myWalls = BlockTags.bind("minecraft:walls");

then

  BlockState.is(myWalls)