The first thing is, don't worry about it. That is probably the most important thing too, as he might not eat all winter if he is in 'breeding mode'.

I personally wouldn't offer chicks. The snake has to eat so many of them to make a decent meal, it's a PITA to be honest. Plus, sometimes they then refuse to eat anything else, ever.

I would first of all make sure his set up is right. Temps etc seem fine, but if he is in a viv, make sure it is REALLY packed out with plenty of hides.

Then weigh him, record his exact weight, and leave him. I would probably totally ignore him for at least two weeks, preferably three or four if you can stand it, and only do essential water changes. Otherwise, ignore him.

Then, quietly, late at night in a darkish room, offer him a med/large weaner rat that has been made very hot head/front only) with a hairdryer. Offer on tongs but not right under his nose, and wiggle it around a little bit. if he doesn't eat it, put it at the entrance to his hide overnight. If it isn't gone by morning, remove and leave him again.

I would weigh him once a month and offer food once a month, on alternate fornights for now. He is an adult snake, and can go months without eating, and the more you offer him the more stressed he is likely to get and not feed. If he does eat the first time you try, offer him again two weeks later. Just watch he doesn't start losing weight/much weight.

I am sure he'll be fine. He will eat eventually when he feels like it, it's just a royal thing.