Any tips you guys can offer?
These are mostly just general tips but all will apply to this time trial as well, also I'm not familiar with your experience with Forza games so sorry if any of these are too basic.
1. If you're still on automatic I highly recommend switching to manual or even better manual w/ clutch, last I checked there weren't any automatic transmission users beating the current time and not too many (although there were some) manual users, and there's probably a 0.5 - 1 second advantage between each transmission setting on this track.
2. Make sure you're using an appropriate tune, as far as I'm aware power upgrades aren't too useful here at Brands Hatch, so look for a tune with stock power output, or anything near the top of the leaderboards should do. When experimenting with builds in the first few days my power build was 2+ seconds per lap slower than my early grip build.
3. Don't rely on the braking line, it's best to learn when to brake by other references, the braking line will have you far too slow coming in to corners where you either don't use all of your handling potential, or you don't use the whole track. Only game I've used it is NFS Shift 2 I think for getting the "perfect" turns and it messed up my braking points for a good while after I took it back off. If you're constantly driving different cars on different tracks it might not be a bad decision but if you're running the same car/track you can keep it off.
4. Don't brake as late as possible to make the turn though, braking slightly earlier and most importantly in a straight line, it gets you slowed down quicker and puts you on a better position to maintain your line, you may lose a tenth or two braking too early and having to coast a few metres but that's better than the second or more you'll lose braking too late and having to stick it around the outside of the corner. If you look at professional racing drivers it's not too often you see them braking and turning at the same time, it's just not as fast.
5. Be able to spot where you're going wrong, or where you're losing time. It's no good if you're just driving laps but not paying attention to what makes for a faster lap, you should always be thinking along the lines of "too slow here", "was braking too late there" etc. and then try something different next time, if you keep practicing the same bad line, it's still going to be a bad line. I tend to switch my rivals up a bit and sometimes I'll race someone a tenth or two quicker, other times I race my own ghost to see what I'm doing better now and get an idea of what my target time should be.
And if you're stuck for a general track guide for this car,
@SlipZtrEm had a great guide in this thread
here.
Controller settings I have no idea about, I'm still running default deadzones with sim steering and have no problems keeping control of my cars, so I'm of the belief that as long as you're comfortable controlling the car they don't really require changing and aren't beneficial to lap times.