I have used Amway's LOC for 40 years and wouldn't be without it. It will clean anything in the house--even lipstick off the carpet-but is safe to brush your teeth with. I mix it in a spray bottle and keep one in each bathroom. Clean the tile with it and then just spray the walls frequently and soap scum won't stick and mildew won't form. I never have to do a major tub or shower clean up.
It will take some soaking and scrubbing at first. I used the old fashioned Heloise nylon net scrubber. (40 yrs ago:) )
To get rid of the mildew already there they have a product called Pursue. Or use bleach and a toothbrush. Be aware that once the mildew spore is firmly entrenched it may take awhile to keep it from growing back. You may even have to clean out old grout and chaulk and redo.
To avoid the worst of soap scum, use Zest. It is a very mild detergent bar without all the fats that are in soap. I started using it when it first came out and my children were preschool. no problems. And it leaves your skin feeling silky clean.
And of course leave the shower curtain open. If you have an exhaust fan use it to help dry the tub area.
THis is so easy, I can't believe the whole world doesn't do it. You really can be a good wife and mother and NOT spend one day a month scrubbing the shower walls!!
God bless