Gaz, your identikit seems to fit with about half the regular posters on here.
You're the same age as me - my story is slightly different. I've been a guitarist since my teens, and started drumming towards the end of last year when my wife bought a kit for our son.
I'd suggest lessons, even if only to structure your initial (re)learning.
You won't have as much time to devote to your drumming now as you did when you were teenager. Accept that this will slow down your progress.
And go easy on yourself - the brashness of youth is not the best aid to honest self-assessment. Technique will come: practice and wait for it to arrive.
Hahaha James! I think you're right on all counts there, btw.
Gaz, I've been playing for a whole two and half years, and I'm 48 too. I've started from nowhere, but the main difficulty you have, as I see it, is that you aren't as good now as you used to be, and I can understand that this must be incredibly frustrating.
Think of it like running. If you don't run, you can't do it very well, even if you used to be Usain Bolt twenty years ago. You can't expect anything else.
I'd imagine that you're having problems with muscle memory and timing, and maybe co-ordination too. Again, go for the fitness analogy: you have to work at it - hard! - and it'll improve. Rudiments, Gaz, rudiments! Slow and correct. Very slow and very correct.
Don't be too hard on yourself (sez me, self-beater-upper extraordinaire). When I have one of my "wail!" days (I'm having one today, and shall shortly take the advice I'm about to give you), I make myself sit at my kit and hit the drums. I don't attempt to play them, as such, because it'll go horribly wrong and then I'll wail even more: I just let my hands and feet go where they will. It's ridiculously difficult to let myself do that but it achieves two things: 1) it proves to me that however important my drumming is to me, it doesn't cause the Apocalypse, and 2) every sound I make is a good one even if it's somewhat unexpected. And then I am able to be kinder to myself, my confidence isn't dented, and I stop wailing.
It's brilliant that you're playing again, and in a band again. I bet it feels like coming home every time you sit at your kit!