Hi Derek,
Why do you think the Instructor rating is the best first option for you? Surely the CPL will give you valuable experience in a more acurate and vigorous environment.
The other point being how do you expect to be a fee earning instructor without the CPL....unless things have changed, earning anything more than a fuel contribution is a no no with a PPL.
Point is Derek, it has to be CPL first then FI or IR, whatever your desire....PS IR can be done before CPL without wishing to patronise, if you fancied that.
Good luck anyway