I'm not sure whether it depends who you adopt with. I was through an LA and they did make a life story book for DD but it was completely inappropriate as in it had no story just lots of photos of extended birth family with no explanation of who anyone was or why LO was in care. I also got it about 7 months after LO was placed so it was fairly useless as by then LO had already been asking questions and wanted to know how I came to be her mummy.
I think its usefulness (or otherwise) depends on the skill of the person putting it together. My DDs SW was perfectly pleasant but completely snowed under due to ridiculous case loads and quite frankly, with hindsight, I would say that putting LOs life story book together was never top of her priority list. I can understand why when she was running across the country almost daily dealing with CP cases but it doesn't make it any easier for the child who misses out on having a useful life story book from when they are first placed.
I did a whole load of research on the internet about life story books when I was making DDs. I nicked the ideas and bits I thought were useful and relevant and added in the extra stuff I though would be useful / would appeal to her and engage her. I'm quite artistic / crafty so doing the whole collage scrapbook thing was something I enjoyed doing and now DD is a bit older we add things in together and cut and stick photos, postcards mementos etc.
A couple of years ago I went on an adoption uk life story course run by Joy Rees. It was very good and I'd heartily recommend it if one comes up in your area. There was lots I felt I'd done 'right' but also a few things I wish I'd done differently when I listened to Joy.
I don't think there's a right or wrong way to do life story books. I think the essential bit is enabling LOs to understand adoption, how they came to be in their family and to feel confident to ask questions as and when they want.
It would be lovely if SWs had the time and resources to really devote their energies to making life story work a priority but IME they don't and its up to us to do it as best as we can.
As for a later life letter I have been asking for it for years. Still no sign...