Habitat, temperatures and shedding all have to do with whether a snake will not eat. Make sure that your temps are correct. The next thing you will want to look for is shedding. If a snake is getting ready to shed they may go off feed until done. Lighting can affect the snakes as they will not hibernate, but without the proper light cycle it can decrease the appetite. It is known that some snakes can go off prey for a year at a time. I would make sure the snake is getting a good soak in a dioralyte and warm water 50/50 and, so he is not getting dehydrated.
Get a weight to be sure he is not loosing weight is most important. Try some different type of prey. Some snakes will start eating if the diet is changed up a bit. Hamster and Gerbil pups may peak his interest. I see you have tried try braining the mice which is allowing the fluid from around the brain area to leak afte make an incision or cutting through the skull. I also see you have already tried dipping the mouse on chcken broth.
If there seems to be weight loss, then a Herp Vet Visit should be done. If you need a Herp Vet. I am going to give you some Herp Vets in the UK: http://www.livefoods.co.uk/Vets.php#Scotland or http://www.ukbeardeddragons.co.uk/vet%20directory.htm
Some snake have been known to go on hunger strikes at different times of the year. Since this is breeding season and he is exceptionally active we see the hunger strikes. This I suspect to be one of those incidents.
1) Keep up with soaks in a 50/50 warm water and Dioralyte
2) get the weight and monitor it for any loss.
3)Try different foods. try waiting two weeks before offering food.
4)If this continues, you may need to see a Herp Vet if this continues and there is weight loss. The Herp Vet may have to tube feed or give a vitamin injection to get him going.