Might have put petrol in my diesel..

ha ha ha... yeah i noticed that!!

Might be worth chucking a bit of two-stroke oil in to add some lubrication.

half a liter of 2 stork should do the job matey

Not entirely in the clear.

There was a customer who did this to his '05 Audi Dizzle. It ran back from the continent on a similar mix of petrol and diesel. From full tank - then when it got to around quarter tank it s*** itself and decided that the injector seal didn't want to be an injector seal anymore.

But really had aspirations to be a travelling collage salesman.

As has been said really try and keep it brimmed with as much diesel as you can.

We used to recover loads of cars which had been driven after doing the same and were fine at first but then broke.

Yeah, newer car... Boom.

I used to pop a drop of unleaded into my L400 Delica with a tankful as various forum reports suggested it was a good way of prolonging (for months, maybe weeks) iffy pump seals - but that was maybe a fiver into a full tank every 2nd or 3rd tank. If it were an old diesel, I'd chance trying to dilute it, but given how modern it is, I'd pump out the tank and then refill it - or, indeed, just pay for that draining service.

This was the advice I was told to stick to on anything more complex than an XUD. The XUD was the example because it was North Africa and it's ultra common there. The common-ish alternative were the VW SDi/TDi types and they were always failing because it wasn't unusual to be sold contaminated fuel at the side of the road.
They often needed hoses and seals replaced, the language barrier prevented me finding out the detail of what they were talking about.

Petrol engines, even very modern ones, seemed able to burn off the diesel and just ran really badly on the dodgy roadside fuel.

What's the reasoning behind the two stoke oil suggestions?

Common rail diesel + anything other than Derv = a world of pain, misery and an empty wallet. Drain it now whilst you still have a working motor

Chap round the corner chucked some kerosene in his Kia people carrier thing (MB dizzle engine) and all was good for a few miles, then it all went tits up as the injectors failed, Cost him £1K to have it sorted

Drain it. On older cars with mechanical pumps you could get away with it. A modern common rail engine though? Nah! Bite the bullet and drain the tank or you could be in for a whole world of hate. If you whip the rear bench out and remove the sender unit(s) then it'll be easier than trying to get it out through the filler, plus you can get it all out.