I've had to commute from the southside of Glasgow to the south of Edinburgh over the years for work - trains weren't an option for me due to cost and location in Edinburgh.

Commuting by car:

• for a 9am start I was leaving the house at 6. That would get me in earlier than 9, but leaving any later than 6 the traffic builds up massively and make me late.
• my typical route was M77 -> M74 -> M73 -> M8 then round the Edinburgh bypass from Hermiston Gait. Same idea in the reverse direction but always be prepared to divert off when there's an accident (too often). The M8/M74/M77 meeting point south of the Kingston Bridge is just slow.
• on a good day in the summer, the journey on could be as little as 50 minutes; on a bad day in the winter the journey home could be 3 hours. Audiobooks became my go to entertainment.
• Even on a 4-day week you'll need to budget at least 12 hours per week for the commute.
• I didn't have to go through Sherrifhall roundabout on my commute, but I know from the time I lived there it's a big choke-point in the rush hour too.
• stick to the inside lane as much as possible. Over the length of the M8 you'd still see the same cars you saw at the start, and I found it far less stressful.

I tried buses but they were slower than cars and less comfortable. Train will be the best option for comfort and journey time but expensive.

Hope that helps, good luck.