Your code example seems quite confused and not very specific as to what constitutes the model.
First, you can't use Switch as a variable since it is a Mathematica function, which you might actually use.
I'm not quite certain about the use of Goto but I don't think you could use it to transfer between notebook cells. You have to use it within a single cell, or within a compound statement, or within a Module as is shown on the Help page for Goto.
Goto may have a few uses but is not generally a good programming method. You could try something like this:
evaluateModel[modelType_] := (If[modelType == 2, Goto[model2]]; Print["Evaluating Model 1"]; Goto[end]; Label[model2]; Print["Evaluating Model 2"]; Label[end]; "Return the model");
But a far better method would be:
evaluateModel[modelType_] := Switch[modelType, 1, Print["Evaluating Model 1"]; "Return the model", 2, Print["Evaluating Model 2"]; "Return the model"]