Are the plants getting at least a half day of sun? What variety are they? Some varieties bear quite late, if the weather cooperates.

Full sun, variety Unknown . If they fail they will make good compost. How late is quite late.

Hard for me to tell in your climate. Where I live, they head up from November to January, depending on the kind. Someone in the UK will have a better idea of your chances.

mine didn't produce florets last year either but I harvested the leaves and ate them as just greens. they were lovely.

Haven't grown it for years but when I did the florets appeared in about March. Perhaps depends when they were planted.Don't give up on them yet anyway.