Then would this be the final solution for what I'm trying to do?

Maybe. Personally I like the using the switch but may need to re-think the auto mode. Probably don't want a 100% dimming meaning when the ambient light level is at it lowest the LEDs will be OFF. Could add a pot to the LDR branch to allow a custom setting of the minimum brightness level of the LEDs.
The circuit works using a LM358 but I prefer the LM6142, I think your project is worth the extra expense.

 

This is the current circuit, I have used a LM358 because fritzing doesn't have a LM6142, but I could still change that if it would be better.
I have also added the pot to the LDR for a minimum brightness.
Anything left to change or should this work?

 

Missing the 47k resistor from the 500K pot to ground and R35 is 220K. I'll have time later to try out the pot on the LDR branch.

 

Missing the 47k resistor from the 500K pot to ground and R35 is 220K. I'll have time later to try out the pot on the LDR branch.

Oops, didn't notice that, thanks for that. I'll be waiting for your results with the pot.

 

Adding Vr1 a 250K pot I can set the minimum PWM from 0 to 50% when the LDR is at max resistance 500K.

 

Here are the values that You need for proper brightness control ........
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Allright, thanks for the help everyone! I have ordered the components and the pcb. I'll let you know if everything works in a few weeks.