Very good idea. I suspect that PsiFox may have it entirely right and I don't want you suing me
Let me try to put it another way.
It doesn't matter whether you are a hobbyist or a pro anyone can sue you.
After all that would mean only professional race drivers needed car insurance.
PL insurance is not compulsory for photographers.
However if you are shooting on other peoples property consider the following:
You drag your equipment bag out of the car at the reception, it swings around and dents the door of the car next to you.
Now the owner is going to want you to pay but his lamborghini has to go to a specialist for repairs.
Do you want to pay the resulting bill personally or claim from your PL cover?
Now when you get inside with your bag on your back you swing around and accidentally knock off the million pound ming vase on display in reception.
Again, do you have the bank balance to cover it as the venues insurers will come after you? Phew I'm insured.
Jst to make matters worse whilst you are shooting some candids with a 70-200 you swing round and clout the Brides Aunts 2nd cousin on the head cutting her forehead open.
Who do you think is going to pay for the plastic surgery at the end of the day? Her, you or your insurer?
Humorous examples but that is the point, we are not able to see what might happen so we insure against potential risk.
To note it only costs about £50 p.a. for £2,000,000 cover so not expensive.