A new work on Medieval Irish Eschatology edited by John Carey is due to be published soon. The work is essentially a collection of primary sources produced in medieval Ireland and covers areas like the afterlife, heaven, hell, and the final judgment. It's a two volume set, running to almost 950 pages and looks like an excellent resource.
Early medieval Irish eschatology is a topic I did some limited research on last year.
This is an essay I wrote on the Chirstological emphasis in early Irish eschatology. I focused on the dominant theme of Christ in the eschatological expectation of early Irish theology.