I lost all my purple sprouting, most caulis and january cabbages to waterlogging, slugs and greyfly, but Dobies are doing a young plant collection, ten each of early white and early purple sprouting, early and late spring cabbages and April caulis for £10. Not cheap, but the thought of no sprouting or caulis is worse!
Might be a useful stop-gap tip for those with new allotments.