Same here, I'm afraid. The alternatives are trying to nudge between car-drivers who've already stopped with a spacing they're happy with, thus pissing them off, or joining the queue of cars at the back and squandering my Magic Scooter Powers.

On the rare occasions when I'm the first vehicle to the traffic lights, I do stop behind the line. Generally another motorcyclist comes in front of me.

There aren't really enough cyclists around in Bristol for it to be much of an issue, usually. It's the hills, I think.