apologies for the multiple posts but I can only take things in baby steps or I get confused :-)
That index record for admin gives a volume and folio number
I haven't seen an admin abstract so have no idea what info they contain but have a couple of will abstracts which did help my research. These are inland Revenue records so may give an idea of what his estate was valued at and how much the death duties were.
Family Search have digitised these but because of contractual restrictions they are only viewable at a Family History Centre or an affiliate library
EDIT can also be viewed at NA as that is an affiliate library
If you have one near you they will let you search and view on their computers and allow you to either download or print the image.
to find your nearest FHC look here:
https://www.familysearch.org/search/catalog/522838?availability=Family%20History%20Librarydo ring before you visit to be sure they are still open (our nearest is no longer in operation as they didn't have enough volunteers)
go there, using the info from the index image on the NA. - year 1828, vol 1 folio 11
scroll down till you see the entry for
Administration abstracts, A-Z, 1828 (p. 1-230, Jan.-Apr.). film 1817904 image group number 8220572
and from there you should be able to find the record on folio 11
The originals are at the NA and can be (
EDIT ordered to view advance of when you plan to visit see reply from Bookbox) ordered online but there will be a cost to that £8.40 for them to look for it and see if its suitable to be copied at which stage they send you a quote to actually copy it which will be at least that amount again
https://discovery.nationalarchives.gov.uk/details/r/C3339375Boo