Formula to solve a complex chemistry equation

"I want to set up a range of values for V_b from which to calculate [H^+ ]."

But your table has values for pH (which is not in your formula anywhere), H^+ (which you want to calculate), and V_b with ?s (but what you wanted to set to specific values).

I would expect a table of V_b and perhaps other constants - so what is it that you actually want to calculate? The attached calculates V_b