I drive the 401-35/115 route every 2 weeks, my son goes to University in Peterborough.
Don't fill up in the GTA, the ultra-cheap gas is in Peterborough where 35/115 ends at Lansdowne (336 Lansdowne St E near Ashburnham Dr). Turn left, and Pioneer and other stations have gas at 8 to 15 c/L cheapter than GTA.
On top of the Oak Ridges Moraine in Kawartha Lakes area, the temperatures are usually 4 or more degrees colder and winter driving can be risky - ensure you have good winter tires and traction control feature on your vehicle.
Use the later model Garmin Nuvi GPS's, as the maps are updated with real time traffic reports. Drives back to the GTA can be brutal on Sunday evenings, especially around Bowmanville/Courtice area - 45m or more delay, use the GPS to try alternate routes, eg. Taunton Road.