Hey there,
Unfortunately Mod B is that module where you're required to over-prepare and use like, half of what you've prepared- which sucks. I'm someone who doesn't walk into the exam with prepared responses, so what I usually do is I allocate quotes to themes of the poem so it would be easier for me to choose 2 poems. Plus, it's less for me to memorise- I find it easier to memorise quotes than memorise full essays. Considering how there are a lot of ideas Yeats explores, narrow the themes down to 3 themes per poem and find common themes- this will become kinda like an essay plan, without a question to refer to and a thesis.
If you're not comfortable with one of the poems, at least know some of the quotes so you have something to work from. My teacher suggested that if you're uncomfortable with the prescribed poem, analyse 3 poems so you still analyse the prescribed poem but you're relating that poem with other poems- plus, you can add more word count by doing so.
Hope this helps!