Wouldnt worry about steering idler unless you can feel the steering wandering while your driving.
Why will the " camcover gaskets need doing by then" ?
If you keep the breathers clean, camcover gaskets shouldnt present problems.
I did mine years ago when I first got the car but havent needed to touch them since, because I clean the breathers regularly.
It is just that I haven't done them for some time as my mileage is now so low. In the past I have found the usual oil in the plug wells, which has prompted me to do them. I must be honest in saying I do not regularly clean the breathing system fully, just the easy top end! If I remember correctly, Serek fully cleaned the breather system about 3 years and just 5k miles ago. That is why I am now thinking that it is the right time, and the easy option, later this year, to get that job done by Serek. BUT, I still may just wait and include these works in MY work plan later in the year.
Once more though I do not have any factual reason for having that job done, apart from previous experience and the knowledge that on the Omega you cannot leave it too long due to the nature / weakness of the breather system, and I have always done it. The expression "peace of mind" also comes into it. I did note once though that a OOF member stated that oil in the plug wells actually does nothing as electricity does not conduct through oil (??) I have yet to prove that