Using fit as computed and formula for standard error here.
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.