Hey mate@ajayon
I had a similar experience the happen to me. I was doing my driving lesson in pinner (Northwest london) and i had to reverse and park the vehicle. I was in complete control of the vehicle and only going1mph on the reverse and car comes zooming past me. I dint even see it coming past. I quickly slammed the break pedal so that there was no collision more so because my vehicle was at an angle and that whole situation made me so nervous. My driving instructor took control of the steering wheel and I panicked if what he might say. Although at the back of my mind I knew a collision would be unlikely as I was only going 1mph. Hope that is b helpful.
Thoughts on reading your post;
Because you are going slow at the time of a crash doe's not prevent a crash, and the impact speed is the sum of the vectored speed's of the vehicles involved.
As a rough rule of thumb, when driving, if you are doing something out of the ordinary, (reversing) the onus is on you to do it safely, even if another driver gives way to you, (which has no need to do) safety is still your responsibility.
Your driving instructor should be teaching you to reverse by half turning in your seat to enable you to look out of the rear window, this enables you to use your peripheral vision to see if anything is approaching from the side's. Mirror's or reversing cameras cannot do this.
Good luck.