I'm in exactly the same position as you!
I'm thinking of getting my 2nd Eng Lit paper remarked as I'm 3 raw marks away from A*. I felt the exam went really well and so I deserve higher. I might also get my first Eng Lang paper remarked (I'm like 9 raw marks away from A* but I think I could get it!).
I think 3 UMS is worth a remark, because, it's about 1-2 raw marks which is little and in such a subjective subject, go for it! Perhaps get a photocopy first and discuss with your school teachers (which is what I'm going to do)!.
5UMS is okay, its about 3-4 raw marks. The subject also matters, essay writing ones are worth remarks, as they are subjective!