One sensor should be enough. I believe they usually mount onto the inside of the window facing outwards so that lights and movement in the room don't influence it.

The simplest way of solving this would be with technically four separate automations. However you can place them all in the same HA Automation using multiple triggers and trigger IDs. (Or have one for the blinds and one for the lights with two triggers each)

I'm going to assume the blinds are somewhat light translucent.

For the blinds use a numeric trigger that fires if the lux value is over some threshold for let's say 10 minutes. That way it won't trigger for every tiny cloud. When triggered lower the blinds.

Add another numeric trigger for moving back up when the lux value is under some threshold for 10 mins. Test to make sure that lowering or raising the blinds doesn't darken or lighten the room enough to immediately have it trigger the other trigger. If it does then increase the difference between the two thresholds.

Copy the same procedure for the lights. The timer can be shorter here, maybe try 1 minute. Make sure that the thresholds are low enough as otherwise lowering the blinds would immediately turn the lights on. I would suggest first tuning the blind triggers and then tuning the light thresholds to your liking.

If you can't set the light thresholds low enough so that the blinds don't interfere with them you'll need a somewhat smarter automation but I'd try the easy way first.