Agreed, just to report back it was a complete doddle. Apart from the fact that after removing the old struts (using a flathead screwdriver to prise off the clips) I then proceeded to presume I needed to do the same for the first leg of the new one, and spent 10 minutes getting it back in place when I realised they really did just push on. Just jammed a spare length of 2x4 under the boot to prop it open whilst I did my stuff, even got my 10 year old to prise off the clips on the second one to give him a taste for doing that sort of thing.
Also, when I ordered the strut I mistakenly thought there was only 1 in the boot in the first place, so only ordered 1. Or so I thought. They arrived last night as a pair, though I don't think anything on the website indicated that they came as a pair. Perhaps they were just being nice to me.
As it turned out, only one of the original struts had failed anyway, with the second one being insufficiently strong to hold the boot on its own. But I replaced both anyway.