Using fit as computed and formula for standard error [here](https://en.wikipedia.org/wiki/Simple_linear_regression#Normality_assumption).

[![enter image description here][1]][1]

    Clear[a, b];
    {a, b} = {a, b} /. fit;
    regressedpoints = a # + b & /@ datalog[[All, 1]];
    n = Length[datalog];
    errors = datalog[[All, 2]] - regressedpoints;
    meanx = Mean[datalog[[All, 1]]];
    Sqrt[(Total[errors^2]/(n - 2))/Total[(datalog[[All, 1]] - meanx)^2]]

> 0.0174645

Not sure about the other value.

  [1]: https://i.sstatic.net/ZuADi.png