The 23-year-old, who joined the Magpies in the summer, has won plaudits after several impressive displays in between the sticks following the knee injury to Adam Collin.
Fitzsimons replaced Collin in the win over Barnet before starting in the defeat to Crewe Alexandra and in the draw at Carlisle United, where he made a string of great saves to keep the hosts at bay.
"I don't think we could ask for a better keeper coach," Fitzsimons told the official Notts site. "He's played in the biggest games. When coaching tips come from him, it sinks in.
"Every goalkeeping coach has their own style, but he suits my personality down to the ground. He's chilled and gets his message across quickly and effectively. He's been a massive part of my development since coming here.
"The four of us [Crossley, Collin and Branislav Pindroch] are always working together and analysing things – right down to the nitty gritty stuff. That's important for all of us and drives us on.
"[The injury to Collin] can happen to any one of us. That's why we've got three top goalkeepers.
"With us up near the top, it was important for me to slot straight in. That's the nature of the beast. You could be out for six months but, straightaway, it can come thick and fast. It's important to be mentally and physically ready.
"I'm delighted with how I've been playing, and with a point [against Carlisle]. I don't think teams will take a lot of points there so to come away with a draw was brilliant after Tuesday."
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