I wouldn't mind if the docking computer had an undock function, not like it would make it OP
to TC though: you do know that you're meant to go through on the "green" light side of the station right? that's always the correct lane so nothing should slam into you head on at least? even 2 T('s can get through simultaneously though there is a little scrapage in that case
This is not true. If you are flying something like T9, T10 or iCutter, even small ships getting through the mailslot are going to be a problem. Even if you stick to the greens. You can ram them, of course, at least in Solo. Though it's still highly annoying. Recently had to destroy a Beluga this way to clear the slot and it takes a while. Didn't see what's approaching, decided to go through and when in the slot I saw it's a Beluga. It was too late to go back and wait. I was in the slot first, it approached anyway.
So I do get the OP and why they are asking for this. It's been asked for a few times already and it is also an option I would like to see. Not because taking off is a problem, I've done it gazillion times in ships of various sizes, but because there is no traffic control in Elite. Or at least it seems so. There is some order to this chaos when you're using DC to dock, there is a total mess when you're taking off. Especially in busy starports. NPC vessels do not seem to be taking the player's ship under consideration.
This is another game design feature where FD shot themselves in the foot, in my opinion. Had they decided to part with the mail slot design and instead have external docking to stations (The Expanse style for example, Starship Troopers style or even current rescue ships style), not only would they free themselves to design ships in a broader range of shapes and sizes but would also avoid creating issues like the one OP mentions. They went for Space Oddysey version and it looks nice in the film because it's done once there. Sure, the mailslot looks cool. The first three times. As soon as the novelty wears off it's just plain boring. But, it is what it is and we have to live with that, so I think it's not unreasonable to ask for auto - take off or at least introducing some sort of order in the mailslot. Or perhaps one mailslot for landing and one slot for take off at least at some point? Surely there's room for two slots sitting one above the other? At least this way all the ships are going in the same direction, there's still chance for collisions, but less so than when all traffic goes through the same slot.