Hi, Mamya!
I presume A. means p=page + litt=abb. for letters as in the Latin-based title B. Litt. etc.
The word itself is hairy though -- at least I'd never heard of it, but it's in "The Bible" (Ch.)!
Have done all except 1 down and 1 across - Guardian of scouts at sea --s-o- and portmanteau that's taken on 18 down visit with queen and lieutenant missing --u-n-l (18 down is French). Have I got something wrong?
You're on the right track with both: you need a Latin word for guardian (anagram of scouts), and tghe other one is a word formed by merging two others meaning s'thing connecting Britain with the Continent!