A few things off the top of my head...
I use a insurance company specifically for people who leave homes unoccupied for months at a time, my normal house insurance will not cover me for more than 30 days if the house is unoccupied.
I have a gardener who keeps an eye on things as well as a trusted neighbour/family who reads the meters and puts the garden bin out.
Timers on lights, and heating (you will need to keep the house at a certain temp esp during the winter), water is turned off and other taps outside off and insulated. Fridges/freezers empty and cleaned doors left a little ajar. Go through your food cupboards and have a clear out, dont want to invite any unwanted bugs. Same with clothing, woolen jumpers etc, put cedar balls in draws. Never leave any washing in the basket! And empty you bin before you leave....never forget that one!
I dont SORN my car, its a a hassle and leave it in the garage. You may want to re-direct your post dependant on how much you get, or you could have someone to check your house and pick post up weekly (or whenever). Think about if anyone can see if you have post behind your door.
If you have valuables either take them maybe to a family members house (but check insurance) or store them somewhere safe in the house. Also sensitive or important documents either put them somewhere safe or take them with you. Have a clear out of
personal correspondence and the like.
I would if you dont have one get a alarm fitted, even if its not monitored its a deterrent, make sure your locks on doors and windows are secure...
Sure I will think of more, I use a checklist done this many many times now and thankfully everything has been fine.