I don't see a problem with an Italki tutor being monolingual. I've used my second languages very rarely when teaching, and almost all of my students are keen to use only English in the lessons. Do sign up! :)

I'm like you and I need to improve my English lenguage, maybe you can help me, and I can help you with the spanish. Well only if you want.:)

What do you thing?

I need to improve my English because in my work is really necesary.

I'd imagine you would need to be bilingual to a degree, every teacher I've seen on here speak more than one language and teach their native language to non-native learners as well as teaching their secondary languages to speakers of their native language.

I plan on becoming a teacher too :)

Italki only requires you to speak one language natively. You can also teach languages you're not native to or speak fluently.