I've been putting in some new pickups but followed a really dodgy guide which has sent me way off course.

Basically I've snipped the wire on the end where it connects to my old pickup leaving the pickup like this:

Have I effectively killed any future use of ths pickup by snipping the wire?

Secondly, the gibson wiring looks much more sophisticated to what i'm used to:

I have no idea how to disconnect the neck pickup here and connect the new wires. it looks like there's a button to release the wires but i can't find it.

Any help would be greatly appreciated
You'd have to pull apart the pickup and hope there's enough lead inside of it to solder on a new one, a scary task for someone that's having troubles with basic wiring . What model pickup is it, out of curiosity?

As far the connectors (which I've never seen in a Gibson, though I haven't worked on anything newer than 2006 or so) you could try lightly pulling outward on the tab that's keeping the connector together. I wish quick connects were standardized in the way they come apart, it's aggravating when you're standing in the hot sun trying to swap out something in a truck and can't figure out how the connection comes apart.
Endorsed by Dean Guitars 07-10
2003 Gibson Flying V w/ Moon Inlay
2006 Fender All-American Partscaster
SVK ELP-C500 Custom

1964 Fender Vibro Champ
1989 Peavey VTM60

[thread="1166208"]Gibsons Historic Designs[/thread]
^Gibson just standardized those quick connects in the last year or so, definitely a good move. The good news is that those connectors are soldered on under the wrap, so if you don't have the quick connects on your pickup, you can just pull the tubing off, unsolder the old pickup, and solder the new one into the quick connect. Then you plug and play.

Those are standard electrical clips so you could buy a whole crapload of them and put them on every pickup and guitar you have to make changing them faster in the future.