I have completed my Masters(5 year Integrated) in Optics recently with average CGPA. I have couple of projects experiences in Theoretical Physics, but no publications. My masters course had rigorous higher mathematics papers yet I find that I have very little knowledge and experience in doing even the undergraduate math, though I am very much interested in it, may be because my course was designed to give more importance to experimental physics. Thus, I started improving math using online lectures and our mathematics stackexchange forum, and I can feel I am able to gain much more than what I could during the course. But many told me not to take a gap by spending time on maths after masters as it'd affect my chances of a Phd admission, as I am already 26.
So is it a good idea to do a second bachelors degree in Mathematics(distant education) before applying for a Phd in theoretical Physics in Europe/Australia ?
Or is there a better way to compensate the time I spend on improving maths myself ?
Note: The reason I was thinking of doing a bachelor's while improving my math is, that way at least I could show that I was doing something while I was away from academia.