With the cats eye tools you should be able to still get collimation sorted or very close even if you in focus quite a distance. While it is not optimum the collimation would have to be better than at present. Yes do look into sag related issues. Sometimes it can be a minor thing that is making things sag.
Focus should be checked every hour when imaging. Minute focus changes occur all night long as you will be aware and this means a good practice of hour checks is preferred. Therefore good pointing is a must for imaging.
Not to worry, when you come down to Clayton we will get you in the swing of things.
