I checked the mustard last night and it does appear to be getting darker in colour though I could be that I was looking for that. I did notice a little separation of what looks like water, at one side of the pot, but not alot. Taste tested again and the mustard is still delivering.
I think my next step will be making up my own blend of mustard and condiments using the mustard powder.

I love horseradish too, it is my preferred condiment with roast beef. I have never made it fresh but have certainly enjoyed it in restaurants. It's easy to grow I am told so I might have a go, I am fed up with the lack lustre commercial products available. I just can't seem to find a really good hot horseradish sauce anywhere.