Hen or roo?

[MagnusT]

We have no idea what it is. It's mostly white with a small splash of grey on one wing

... these are all the chooks (we got the eggs from our neighbour)

 

[MagnusT]

Yea I agree. I have four chicks two of which are slower to mature. The other two have matured a bit faster and had small yellowish combs and no wattles, their faces were also pale and not red as you'd see in an adult bird. I'd say if the comb and face were more red than yellow you'd have a cockerel. Also in a young rooster you'd start to see wattle development those would be red as well.
Other things you could look for are: does this bird have the most dominance or does it tend to bully the others, others find that their feet may be bigger than the others in the flock, younger roosters also tend to take a little longer to feather out than the pullets.

This one is def the lowest in the pecking order. Also a fair bit smaller than the others.

 

[khloee]

This one is def the lowest in the pecking order. Also a fair bit smaller than the others.

I would say you have a pullet. I looked at your picture again and I'm still thinking pullet. At this age if you had a rooster you'd start to notice more redness in the face, comb, and wattles.