Some idiot put the locking wheel nuts on my car with an air gun, the mobile tyre fitter managed to get 1 off and fit a new rear tyre but not the other rear. Car is booked in for Thursday to get the other one sorted, would it be daft to drive with different wear on the tyres before then?

Not something I’d choose to do, but if it’s only a couple of days and you’re aware of it I would.
Just be cautious and drive steady, especially if it rains.

It’ll be fine, especially if it’s FWD.

Have you seen the state of some folks tyres? Yours won’t be the worst.

(But not ideal)

Also if one tyre is borderline illegal and the other has 7mm of tread it could cause problems with things like ABS and active all wheel drive systems if present.

Thanks all, I can probably get away with not driving it till it’s sorted but might have to on Wednesday so good to know it’s not a really bad idea!

I would love to know often does each axel have both its wheels travelling the same distance. With all the corners, roundabouts and parking going on and the differential (assuming it is the driven axel) doing its thing I would imagine that there is very little time spent in that scenario.
This confuses me when tyre fitters and alike often claim it is bad for the car to have differing tread depths on each axel especially when I have driven the car there and you can guarantee that the front left will have more wear than front right due to roundabout abuse etc.
I can understand uneven breaking performance and wet weather performance from differing tread depths but I do wonder how much of this advice is really just about selling another tyre.