I'm doing English and Literature at the moment; in my opinion, it's certainly worth doing. Like you said, you have English as a 'back-up' whilst Literature is just a subject you thoroughly enjoy. If you love the English language, I'm sure you won't find English as dull as you think. And if anything, I've found that they both work hand in hand; my English is dramatically improved by my lit and the same the other way around. The workload isn't too bad, it's just the amount of practice essays you have to do. At my school, there's a large cohort of English students, so the subject is quite fast paced. But with Lit, it's very chill and just easy going given the smaller cohort of about 25 kids.
Even if you choose to do Legal Studies and then pick up English in year 12 that'll be okay as well. I only picked up English in year 12 and with the advice of some awesome AN members (VivaTequila - you should talk to him!), I'm doing fine. Like ktrah said, English teachers like structure whereas in Lit, it can vary. For me, Language Analyses are the toughest to do because they're so different from regular text responses and what not.
The different styles of Lit and Eng aren't too confusing (at least for me), like I said, they compliment each other. For example, Passage Analyses and Language Analyses. Although they are very different, they both teach you how to analyse language, just in different forms.
This is just my opinion, and I'm sure everyone who does Lit and English have different opinions. Hope it helps!
Edit: Just realised you must have already put your subject swaps in. What did you end up choosing?