Sounds like you've done the right thing, attending the self-defense course.
I was not aware that you lived in the U.K. I have heard that firearms, etc. were illegal in the U.K. That is a shame. One wonders sometimes what lawmakers use for brains. There are some places in the U.S. that have similar bone-headed laws, and, like the U.K., the courts sometimes favor the criminal and punish the victim.
I have heard that there are some things like walking canes and stout flashlights that a citizen can carry in the U.K. that can be used as a weapon, if necessary. I wonder if an umbrella with a spike on the end would be legal to carry, and secondly, would it be legal to use it as a weapon when attacked. Maybe it would depend upon the primary motive for carrying it. You might want to verify that, but if it is true, it might be worth knowing. It might provide you with some options.
I am curious, what would the courts have to say about it if you were attacked and pulled out an ink pen and stabbed your attacker to death with it, or strangled him with your belt?
To be sure, the best thing to do is keep the attack from happening in the first place. If that doesn't work, it would be nice to have something that you can use as an equalizer.