There are one or two services that have you chasing a few yellows but reds are less common. However try this. Spoiler: HST run Firstly in the options menu switch off the next signal aspect hud display It's cheating with that on. Select the 1K34 8:19 Paddington to Newbury. Take your time setting up the train making sure you switch on the AWS. Wait a little while and don't depart until 8:21:30 - you're only 2.5 or so mins late. A 166 should depart ahead of you. Prepare to concentrate on the view ahead for a lot of the journey. Don't get too complacent with the yellows! You can try and see if you can make up for the delayed start (but sticking to the limits) and arrive at Reading on time, it's very tricky. Since it's a Newbury bound train, if you want to, you can stay onboard and drive it beyond Reading taking the junction to the south. Until it chucks you off.
There's a few freight services that'll have you switching from relief to fast and vice-versa and you'll get held-up to do that in places. Been held at Slough going west a few times in the HST too. Can't remember the services though.
I'll admit I usually play with it turned on, but I'd like to start taking off some of the assists as I get to know the routes better. Don't think I could ever turn off the next speed limit indicator as my eyes just can't make out the trackside markers most of the time (exception being the German routes, where they're helpfully not tiny, and actually at eye-level). Is there any way to turn off the next signal aspect, but still have it show the distance to the next signal? I know in real-life this would be down to operator knowledge, but I'm not quite there yet lol.
Yes, you can set 'Next signal HUD' on, but 'Next signal aspect' off. The signal will just show as a grey blob in the HUD. Without any HUD signal indications at all, it's definitely a more immersive experience; you really have to concentrate on watching for signals, and this gets easier with practice. It's surprising how far away you can successfully make out the aspect of a signal, even in poor weather. (Except on the Peninsula Corridor route, where by the time you can make out what the signal says, you've already gone past it. You can see why they're so keen to roll out cab signalling.)
Adding to the supportive comments above and if driving the 166, if the next signal is green then go at the speed limit, double yellow slow to about 60, single yellow 40- that should be safe enough. Adjust appropriately for heavy freight 66s or fast hst. Bear in mind that currently double yellow may also indicate a divergance- they should be flashing if this is the case but this is currently not implemented in GWE. Turning off signal hud marks a shift in mindset from driving with reference to the hud, towards driving according to what you can see out of the window. This means that you will be driving a little slower, and a lot safer, because you will be assessing whether your speed is appropriate more. So as part of this mindshift change if you are a little late, so be it. Better a few minutes late than driving in an unsafe manner- and truth be told once you get a bit of confidence and practice you wont actually be any slower.