It's years since I had a plot with clubroot, but sowing in cells/pots helped, and growing-on in 10cm+ pots before transplanting worked even better.
There is a cold war over sprout flavour - some people think that the sweet ones that children "like" (ie. will eat) are fine and good.
Others like me think that the mustardy tang of a proper sprout is the only good reason to grow them. If I want sweet I grow cabbage, but for a roast I want punchy flavours.
Anyway there is a middle ground where the red sprouts are - medium sweet but have an extra flavour to compensate for the lack of tang.
Red Bull are well worth trying for this.
Rubine has the most red flavour but the sprouts are small and the plants are too. Falstaff has been a bit too wishy washy for me.
There are a few others that look & taste like tiny January King cabbage - which is fine except I already have the real thing through the season.
I'm going to bury my "Red Darling" stick from Lidl (a bit sweeter than Red Bull) - hopefully it will root and the remaining embryo sprouts will provide seed for 2019.