Probably top arm bushes. Mine always break before squeaking because I live up a rough lane...
You won't be able to "see" anything if the bushes are OK, and even if they are knackered it is pretty hard to spot it.
If it is better in the wet (water lubricates and stops the squeaking) then it is pretty certain. If it is more than squeaking (knocking) then it is either top/lower arm or arb drop link.
I find it damn hard to diagnose which bit it is. As I do it myself, I just replace the lot every two years or whenever the noise starts again. Cheaper than getting a 1/2 mile lane resurfaced.... A specialist will be able to pinpoint it.