Also, I'd like to just add that the idea that "thugs" or those involved in criminal lifestyles are always going to be untrained is a fallacy. A lot of those guys do go out and train in various MAs etc. and their skills are arguably made more formidable by the applicatory environments in which they use them; they're not all like that, but I know quite a few guys who are. Then again, if you're in a situation where they're looking to do you a mischief you fucked up a long time ago...
Personally I think the majority of "self defense" situations that the average man is likely to encounter, is from drunk young men in the bar; your greatest weapon of defense is situational awareness and common sense in this case.
For what you are wanting to gain/obtain you will need to go and train in a gym with people. If you then decide to supplement this training with some video stuff, then that is a different story. Freddie Roach's videos are quite good and not overcomplicated, good supplementally IMHO. A video isn't going to give you critical feedback, make live adjustments to your stance/movement/balance/angles and so on. A video can only show things from a 2 dimensional angle, whereas IRL you are dealing with a 3 dimensional dynamic sphere of bodyspace.
You mention you've boxed and kickboxed before, how long did you do either one for and were you competing frequently or just training casually?
You say "making sure my punches/hand eye coordination/footwork and headmovement are still up to scratch if I ever find myself in a situation where I have to defend myself." The most efficient way to do this is going to be live sparring IMHO. And as you've mentioned it's been confrontations with drunk/disorderly types I'd highly recommend doing some stuff to develop the "top 2 inches" for this kind of thing as well. If you can lay hands on it, Rory Miller wrote a book called Meditations on Violence which has some really good concepts for handling some of these kind of situations using deescalation techniques; for me my personal "lines of defense" would go like this (progressing to the next one only if the previous one has failed):
Avoidance (ie. situational awareness etc., I can see/tell it's a bad environment, some of the guys are getting too drunk and agitated, Spidey senses are tingling, whatever so I move on to another bar or call it a night or do whatever to remove myself from the potential negative situation before it's even begun. Why spoil a good time on someone else's bullshit?)
Verbal/non-confrontational deescalation (ie. I didn't leave when I should've, or things escalated too quickly to do so, situation sprung up unexpectedly or whatever, so now I start employing some of the aforementioned stuff from Miller's book. Things like identifying the situation are very important - is this guy just posturing or looking for self-validation? A lot of drunk young men are just doing that, Miller refers to it as the "monkey dance". You can sidestep it some of the time, like a guy teeing off with "what are you looking at?" Miller suggests responding with something to defuse things such as "Oh your shirt, man, I used to have one just like it... My ex gave me that shirt... Man I hated that chick.." which can take the situation in another direction. Remaining calm and acting slightly bored with the situation as well (Miller calls this the "big dog strategy" or something along those lines) can help a lot for me when combined with targeted deescalation verbals.
Physical deescalation He's laid hands on me, or is about to. It's out of my hands now, there is going to be an altercation. I do my utmost to quickly restrain him using grappling and then start verbally attempting to deescalate while keeping him secure. Wrapping him up and saying "come on bro, I don't wanna fight you. Just chill out and I'll let you up, we'll get another beer. No drama". If it comes down to this, this has worked a LOT for me; if he's there with some buddies and you're worried about them turning on you sometimes it can help (in my experience) to immediately turn to them once you tangled him up and start saying shit like "bro, can you help me calm your mate down? Think he's just a bit too wasted, you wanna give me a hand and we'll get him up" or something like that. If you can get it in, it often defuses the other guys as you're being completely non-aggressive and showing that you're not looking to hurt their friend or fight him at all.
Neutralization All of the above didn't work, or the situation skipped right past them all. Choke him out. Or, in your case, drop him. Either way, it's not really until this stage that you even need to fight IMHO. I still prefer to use grappling at this point because if somebody calls the cops and the other dude's face looks like a stepped on tin of tomato paste I'm probably going up on charges. However if the cops are called and everyone around says all I did was try avoid the fight, and then when he wouldn't let up I held him down and then he stopped fighting (bystanders usually don't realize you choked him out unless it's a really overt choke), I'm probably not even going to be bothered by them beyond a couple questions; you can even often "deescalate" this hassle with comments like "Yeah, I think he just had a little too much, I'm sure he's a good guy, I'm not looking to press charges or anything" etc.
Of course, situations vary and it's never always like that but it's kind of a conceptual guideline for dealing with aggressive drunk dudes that has worked well for me more often than not. So being that that was a large part of your concern, I thought I'd mention it. Needless to say, it's a very condensed and concise version of the steps, there's a lot more to any of them than I can explain in a forum post, application IRL is varied and different every time and nothing in life is a step-by-step, and nothing works 100% of the time so YMMV. Hell, even my mileage has varied. But most of the time it's worked for me. If you like the sound of it though, or are interested, I'd suggest reading Miller's book if you can, and/or just thinking about the concepts and principles involved in what I've written up there, and how you can adapt them to suit yourself, your strengths and personality. Make your own steps.
And out of everything I've said here, the number one most important thing I think I need to mention is: Nothing works 100% of the time, and I have taken plenty of lumps. I'm not Superman or Robocop, I don't win every bar fight, shit doesn't always go my way. But in my experience using this kind of stuff exponentially increases the odds in my favor of it going my way.
All the best with your training, anyway.
M.O.B.F.O.E. - Money Over Bitches, Fitness Over Everything