Thank you for your replies. They are in a small pen (3*6 feet) in the garage at the moment, but I have a larger pen at the side of a shed, its an old brick and wire dog run, maybe about 12*8 feet. I don't like limiting their foraging and always think chucks do better on grass, but never mind, can't have everything I guess.
I seem to have ended up with a some cross-bred maybe cockerals/maybe pullets, so will put all these in there with them. Hopefully all will be fine, and it'll give my boys a chance to fatten up if they're not all running about the place.
I would like to operate a closed flock, with only hatching eggs brought in from outside, so this ought to be a bit of a one off. Although obviously there's all the wild birds carrying lord knows what!

Will move them over tonight, I guess they should be ok for a few weeks, I'll keep them there till I feel too sorry for them or they fatten enough to be worth eating!
...does anyone need a cuckoo marrans, light sussex or buff sussex cock? (Not for eating, I can do that myself!)