As she drove down the M74, she suddenly felt uneasy, and sensed something had happened.
When she arrived, she found out Norma, 64, had passed away from bowel cancer just as that feeling had come over her.
Now the memory of that day, June 8, 2012, will help Gillian in her goal of reaching the finish line in the Edinburgh Marathon this weekend.
The 34-year-old mature student, said: "I was driving down to see Mum and it was about 3.30pm when I got this weird feeling and thought, 'OK, that's a bit strange.' I kept on driving and then I got a call from my dad about half an hour after that.
"He didn't tell me at the time because I was driving but she had passed away before I even got there.
"I got there about half an hour later, and my dad told me she had passed away about 3.30pm."
Gillian, who is in the third year of her four-year microbiology degree at Glasgow University, and her six-year-old son Caeleb live in Glasgow's West End.
They moved 100 miles north from the family home in Carlisle when Gillian decided she'd had enough of her call centre job and wanted to retrain.
Norma was diagnosed with cancer at the end of January 2011, less than six months after her daughter started an HEFC course at Tyne Metropolitan College in Tyneside, a stepping stone to a full degree.
Despite it, her mum urged to start the course at Glasgow University and was insistent to the end that she keep going.
Gillian said: "Her last words to me were, 'You have come this far and don't let this get in the way of it. It's something you always wanted to do and you're doing it now, so just keep going and don't give up.'
"There have been some moments when I have been so stressed but I have just thought back to what my mum said and that has kept me going."
Throughout Norma's illness, Macmillan Cancer Support were with her and her family to offer advice and support.
For Gillian, studying in Glasgow, they stepped in when she couldn't.
She said: "They came in to see my dad and mum and my sister as well because she was finding it really hard.
"They sorted out help for finance for a car that was better for mum to get in and out. There was all the advice they needed and they were there to talk.
"Every time I went down, my dad would say, 'Macmillan were fantastic again'."
After her mum died, Gillian struggled through the hard times but knew she had to keep going.
As the months passed, she began to ask herself how she could honour Norma's memory and say thanks to Macmillan.
Then she had the idea of raising money for them in the Loch Ness marathon in September last year.
Gillian said: "I thought the Loch Ness marathon would be perfect because it was held the day after Mum's birthday.
"She used to love running. She would be out when she was younger going for a run every morning. I used to absolutely hate running. I never used to be the fittest person either so it helped me get fit."
She ran the whole 26.2 miles, forcing herself across the last seven miles when she was ready to give up, and up the hill at the end to the finish.
Gillian said: "I think it was mum who got me through it. I probably would have given up otherwise.
"It was her inspirational words that kept me going."
With the Edinburgh Marathon approaching, Gillian is fitting in 10-mile runs between going to the gym, studying and looking after Caeleb. Her son has also helped keep her going when times get tough.
She said: "He was really fantastic and would say little things like, 'Ah, don't worry, she's up in heaven with Mr Moon and he's looking after her.'
"Our dog died the month after Mum and he'd say 'Ben is up there with her. It's fine, they're all OK and they're together'.
"Every time he'd see the moon in the daytime he'd say, 'Gran's looking down on us'."
Gillian's life has settled down now and the Edinburgh Marathon, which is being held in partnership with Macmillan Cancer Support, is a major goal.
Her mum's determination has kept her going through difficult times and she hopes it will carry her along the full course on Sunday.
She said: "Macmillan gave extra support to my family at the time that I couldn't because I was studying so hard.
"I wanted to give something back to them the best way that I could. I used to think 5K was hard and now I'm telling people I'm going for a quick 10-mile run.
"It has given me a push to get through uni as well because when you get so far through something, why give up when you've gone that far? So keep pushing.
"Macmillan continued to help our family and they're also helping me. I also want to give awareness to other people as well that Macmillan are out there and they're there to help."