I did a double major as you Americans call it in mathematics and physics, and if I had to do it again I would definitely replace the physics with computer science. Double majoring is only worth it if you pick up a useful and practical second major.
And I will give you another piece of advice - physics will not help you in the slightest in that career aspiration.
Most people have this impression that undergrad physics is similar to engineering. In reality physics is much, much closer to mathematics. Certainly you will learn (mathematical) theories that say meaningful things about the world - but this is different from learning how the real world works. The difference between engineering and physics is even greater than between something like biology and medical school.
Additionally no matter what your uninformed teachers and salesmen at physics departments tell you, physics is not an employable degree. I have Physics PhD friends (and this is a common thread over at physics forums) who have been unable to find any job in the tech sector despite all earnest effort because they are not qualified whatsoever for engineering jobs (anymore than a biology graduate is qualified to be a doctor) and they are way too overqualified for technician jobs.
Physics graduates have high employment rates but virtually none of those rates involve the tech sector, except perhaps in software development but you will have to compete with CS graduates there, and you will find that most physics graduates actually work in the financial sector. An engineering or CS graduate can literally do everything a physics grad can do but a physics grad can do little to nothing in the tech sector.
There is nothing hard about undergraduate physics per se - a good engineer or mathematician can easily hobby self teach themselves undergrad physics, which is why I feel the physics major was useless to me. Hence why I now tell anyone interested in physics that it is better to accept the trade-off between passion and job prospects and go into engineering.
Finally, one other warning I give to all prospective physics majors and it is this: forget about the Brian Greene variety of theoretical physics that is glamorized in the media.
Things like string theory and quantum gravity are, aside from being useless mathematical theorizing that isn't going anywhere experimentally, so arcane that you will probably have to study until you are a 30-40 year old before you can delve into them in any detail. People like Lubos Motl are able to learn those things at a young age because they are cognitive freaks - Motl was a competitor at the International Mathematical Olympiads and that is the level of talent required if you want to approach the deep ends of high-energy physics in your 20s - but most normal theoretical physics PhDs will struggle with elementary string theory, and that sh1t is becoming more and more arcanely mathematical and therefore inaccessible to normal human beings by the day.
