The Batman and STEM stamps are very recent USPS issues and the 2 cent stamps are still current issues (I have several waiting to be used. All are probably best just used as postage.
The British booklet stamps are good for a first class letter with no permanently affixed value, much like our Forever stamps.
The British have been using stamps like that for many years. I think they started using them around 1990. The booklet probably does not have much value other than as postage.