Just saved myself a little time. Rather than walking a few kms to the Sofia train station I was told it is much quicker to head down to RILA
(not sure what it is) to get a ticket.
61leva for a sleeper train from Sofia to Istanbul. The "491" departs
Sofia at 19:10 and arrives in Istanbul at 08:19.
I’m interested to see how the border crossing goes and how much euro i
have to hand over for the visa – apparently it is 20 euro