A lot of journals, as well as being available in print, are available online and can be searched via SOLO or eJournals A-Z.
Below are a few of the top journals for Celtic but you can find a longer list on the journals page of this guide.
As well as book review sections in journals, you can look at literary papers or magazines for new titles, for example:
O'r pedwar gwynt (a Welsh literary magazine) on display in B. Per. and The Times Literary Supplement (TLS) - prestigious weekly literary review published in London on display in P.R.R.