Manager Gary Johnson admitted his Robins are now facing a crucial upcoming series of fixtures that will decide the fate of the season and which end of the table the team will be competing in.
Carl Winchester found the net at Meadow Lane with a superb first half strike, but a second half burst from the Magpies saw them take all three points and remain top of Sky Bet League Two.
Cheltenham now face Cambridge United (Tuesday) and Forest Green Rovers (Saturday) during a key week of crunch league fixtures.
And Johnson knows it is likely to be a pivotal week for his side as they look to climb up the table.
“Our fate, and what end of the table we will be competing in, will be decided between now and January and how we play in this next set of games,” he said.
“We’ve had two tough games recently against Luton and Notts County. Now we have got to see if we are better than some of the teams we are going to come up against that are around us.
“It is a bittersweet day,” said Johnson, reflecting on defeat in Nottingham.
“At times we gave as good as we got, against a strong home team who throw numbers forward.
“We were disappointed with their first goal we conceded because at that point in the match it was very even. I’m pleased we got a goal back from some very good play.
“We had two big chances at the start of the second half, with Danny Wright’s header and then Harry Pell hitting the bar. We’ve had opportunities.
“Notts County looked busy and dangerous and I felt little bits of naivety hurt us.
“We didn’t pick up at the corner they scored from and we work hard on our set plays.
“We’re a bit naive when we are marking players that have had good experience at this level.
“We gave away a poor free kick for the second goal, and the third goal we don’t track runners in the box and they win both headers. But we’ve come here and created opportunities of our own."