If you are going the home brew version I agree with leger, hydro shop for the win. If you don't want to use a water pump, you can use gravity pressure, but if a valve fails it will cause the water to flood out. Pumps only pump when they are powered, better for long periods of time if you can guarantee power supply. For a timer you don't want one of the clicky ones like https://www.amazon.com/gp/product/B00MVFF59S/
because the least amount of time they can run is 15 minutes, not very granular. Something like https://www.amazon.com/dp/B00MVF16JG/
is granular down to 1 minute, but it only has 8 "programs" which I'm not sure is enough for a watering schedule. https://www.amazon.com/dp/B0184CG9K0/
is a short period timer, you can turn things on at max every 30 minutes. No matter what system you use you will need
to experiment and dial it in for your specific setup. How much water is being pumped, how much water the plants can drink. There are a few threads on DIY https://www.icmag.com/ic/showthread.php?t=252172
for example, but it's really not wicked complicated. If you do go this route know you will need to flush the system probably once a month to clean out salt buildup.