UKH

I have a new road bike (new to me, not actual new) and the front wheel judders slightly. First noticed it under braking and on rough surfaces but also judders a bit when you lift bike off ground and tap the front wheel.

Skewer is tight

Headset is tight

Bearings are good

Could it be that the spokes need tightening? They're all equal at the moment, but could they all be slightly loose causing this?

Or some other possible cause?

If you stand next to the bike and hold its stem or steerer with one hand and grasp the top of the wheel rim with the other then push/pull the wheel rim away/toward you, is there any lateral play in it, or does it feel totally solid? It could be that your bearings feel completely smooth to rotate by hand but you just need to increase the load on them slightly to compensate for them having worn a little. This is done differently for different brands' hubs but is generally straightforward. There is a page on Sheldon Brown's old website on wheel bearing load that may be useful. If you're concerned though and can't easily identify the issue I would take it to your LBS, just in case it is something safety-critical.

How true does the wheel look when you spin it?  Can use a trimmed cable tie on the fork to check quite accurately against the rim.  Am assuming it's rim brake as its QR.

As mentioned above, bearings can sometimes only show roughness when loaded.

Spoke tension can be compared with the rear.  Should be a fairly high pitched twang (loose spokes will be noticeably dull when plucked), but don't think that would cause the symptoms described.

I'm not too sure what you mean by judder. 

Is the fork sound? is the wheel rim sound - I'm thinking to rule out cracking in both cases.

Perhaps brake bolts - the calliper bolts if it's disc brakes. Also check the bolts/centrelock on the disc.

If it's rim brake then check the pad bolts, and the calliper bolt.

I recently had a problem on an mtb which I asked about on UKC. The quick release kept working loose. Eventually turned out that whilst the quick-release lever felt tight when levering it shut, it could still be easily rotated by hand when shut. I replaced the skewers and all was good. I’m not sure exactly what you mean by “juddering” so perhaps I’m on the wrong track - I think a loose wheel would be noticeable either as a wheel wobble or perhaps by waking up in hospital.