The front wheel on my main bike was feeling very grindy, it’s a shimano 525 hub. So I took it apart and some of the bearing ball bearings were like half balls so I threw those ones away & greased it all up and put it back together, there was probably about 3 quarters of full circle of bearings on one side and a full circle of the balls on the other.
Will I die if i ride it & is it essential to get some more bearings as soon as possible?

Won’t it wear unevenly and probably a bit faster than usual? It shouldn’t explode randomly or anything. Given the state you described it being in, the cup might be worn already, so take a look at it when you get new balls to put in it.

i would put more in, missing one isn’t an issue but more.

take some from the full side and put them in the other side..?

Do you reckon it’ll be Ok for a 30 mile ride tonight, a bit off road but nought too strenuous.

Should be fine.

Is your life insurance up to date?