Okay I tried it again with successful results! 
I used ASM and Skid Recovery as I was using a DS3 and it's hard to ease the throttle out of corners consistently.
Fuji Speedway: This was straight forward, I didn't win by a huge margin but it was comfortable enough. The first part of the track is easy enough although the last section can be quite a handful. I won by 3 second, roughly the same as my first attempt.
Tips: Don't have many for this track however you can make up plenty of time on the long sweeping right hander. My average lap times were 1:15's/1:16's for comparison.
Daytona Road Course: Very easy race. You can outbreak the AI fairly easy and the end result was that I won by 10-12 seconds. Pretty comfortable win.
Tips: Driver hard into the second corner and also the fourth corner. Other than that it should be a comfortable win. My average lap times were 1:09's with High 1:08's occasionally.
Cote D'Azur: Has trouble with this my first race. I was never able to keep up with the AI. This time around I lowered my ratio to around 300 Km and just went hard. I managed to get in the lead on the first corner which helped increase my confidence and keep my laps steady. I ended up winning by 3 seconds, fairly comfortably. 3rd place was roughly 10-15 seconds behind.
Tips: Don't forget to floor the accelerator on the straights. Even though they're short this is vital. I was a bit apprehensive on the throttle at the beginning and couldn't shake the AI. Upon driving harder on these straights I managed to go from 1:18's to 1:16's. Also, drive smooth after the tunnel. You're better off to have a slow lap than hit the wall.
Nurburgring/GP: Won again, same as my first attempt. Although, the AI would always spin on the final chicane. Exactly the same as my first attempt. This resulted in me gaining a lead of 1:20ish and lapping a few cars. I hated this track though and it is very hard to pull 'Authentic' lap-times on par with the AI. The bumpy circuit can cause headaches and gives a similar sensation to oversteer on these corners.
Tips: Be wary of the Double Hairpin, and the corner which comes before the one prior to this. These are very bumpy and may result in going off the track, so take it slow. If you are having trouble with this just cut the chicane at the end. I know it may be cheap but it is better than risking the competition.

If you don't need to do this great, 👍 But for less capable drivers like myself the option is always open. My average lap-times were 1:30's.
Monza: After failing outright on my first attempt the second time I won fairly easily. The first race I was in the rain, which should have been easier (Yes?) but I lost a lead of 40 seconds and then got behind by 15 seconds somehow. This wasn't an issue this time though as it was sunny (Thank God,

). I was very casual, spinning out and hitting walls yet I still was able to keep a lead fairly easily. I won by roughly 5-10 seconds but it could have been 20+ if I was concentrating and not fatigued from the prior races...
Tips: Fairly easy, the main places to pull ahead are the final three or so corners in a group near the end. It's possible to gain a 1 second advantage here. Aside from that just race hard, if you fall behind don't fret too much as you can get in the lead on the straights with ease. My average lap-times were 1:20's.
Suzuka: Haven't done it...
I also found the championship much easier this time round as there wasn'e one AI driver who dominated like in my last attempt. It was infact so even I could have left after just four races and still won. I certainly think this had some impact on my success in this round, along with my better driving of course. 
I hope this is of help to anybody attempting these races, however terrible my recollection of events and tips have been. 
Here's a useful link to good setups for each race in the series too. https://www.gtplanet.net/forum/showthread.php?t=142091
Good Luck!