Sunnyjac, she absolutely couldn't claim her right of way when there were moving vehicles occupying the road space where she intended to drive or moving vehicles clearly heading straight for the road space where she intended to drive.
Doing so is aggressive and dangerous driving and the matter of right of way is completely irrelevant. The only relevant facts were the moving vehicles/oncoming traffic and their proximity to the OP. As the OP could describe the colour of the clothing of the shouty driver and was able to explain her (faulty) rationale in sticking her nose into moving traffic without apparently shouting back at the woman, she didn't have an opening in the traffic that would have made it safe to proceed.
Every car turning out of the side road would have needed to look and check if the way was clear. Either because there was no traffic on the main road or someone was waving them through. OP deciding to stop waving people through by moving forward so the next person could see they couldn't move out isn't "nosing into traffic".
DappledThings
I was just driving along and a funeral car pulled out slowly from a turning. They had about 10 cars behind it which were possibly all part of the party, so I slowed down and let a load of cars through. Now this was a residential road and I could see some other cars had joined the back of the queue. I started easing forward a bit as if I kept waiting there letting all the cars out I would be there ages and needed to get home, also I wasn't to know if they were all part of the funeral. I had right of way as they were in a side turning, but sat there patiently for a while.
OP
She was not doing any waving through. She had stopped and was watching. Then she nosed out. She describes her actions herself.
And since every car coming out of the side road clearly wasn't looking to check for oncoming traffic and was ignoring whatever signage there may have been, the possibility of a crash was the likely result of proceeding.
She could see the line of moving traffic approaching on the side road. She did not say she saw enough of an opening to allow her to move. What she said was that she decided a certain number of cars was enough for a proper funeral procession and that she was anxious to get home. She should have stayed put. Her decision to proceed was not based on traffic conditions right in front of her own eyes. Neither of the factors she took into account should have been elements of a driving decision.
The likely result from enforcing the rules of the road on someone who isn't obeying them is a crash. Sticklers for the rules are often as dangerous as people disregarding them.
The only guide to safe driving when faced with an irregular situation such as the one the OP described is defense - i.e. letting them all pass until there is enough of an opening in the traffic to proceed, not an attempt to claim your rights or to regulate traffic in any way by means of your own vehicle.