My son nixed the idea of turning the power on and off as it would put a strain on the TV circuitry, thus confirming your caution. He insisted I look up the owner's manual on how to set the automatic timer. Dang. He read the manual only once when we bought the TV more than a decade ago, he'd moved Stateside 5 years ago, and he can still remember the contents.
I had to borrow the SONY remote to access the time block functions. All my remotes were stolen along with a VCR, radio-amp and laser disc player some years ago.
Anyway on the SONY TV one can set the internal clock then go on to a timer block to set the time and channel for the TV to come on automatically. If the timer is not reset it will turn itself off after two hours. It will continue with this setting until the time block is cleared or reset. I would have preferred a longer ON time but this will have to do.