Since I bought two packets and vials of both respectively, I'm debating mixing them!
Rather than mix, I would recommend perhaps doing a split batch and fermenting one half with each strain so that you can compare the differences.
I used to use lots of Nottingham, but after doing a couple of split batches with WY1968 I've come to the conclusion that I don't like the flavor profile of Nottingham. Too fruity and tart for me.
You can really taste the differences if you ferment the same wort with different yeasts.