I really want a first. I've had firsts in my English essays, and Spanish lit essays, which are in English. My Spanish isn't fantastic but middling 2:1. Am I shooting myself in the foot by doing JH? I could easily switch to straight English.
What about employers? Is the risk of it being very difficult to get a first worth having the extra language when I'd have more chance with straight English and if I wanted carrying on Spanish in my own time?
Has anyone had to deal with the issue before?
I really want a first too. For some reason every single thread seems to be related to getting a first at the moment, must be that time of year with exams coming up... if you feel the Spanish component of your degree is dragging your marks down and you feel you don't want to do Spanish as a result, then don't do it. The value of having joint honours in English and Spanish is completely relative to the job you apply for - if you want to work in the Spanish embassy, then perhaps Spanish is a good thing to have, if you want to work in a library, they probably aren't going to be to bothered about if you can count to 10 in Spanish. (Admittedly I have no idea what kind of jobs people get with language degrees so I'm just making jobs up here) I don't particularly think that employers consider joint honours any harder to get a first in compared to a single degree...
Why do you want a first? Do you want to become an academic? If so, yes, drop Spanish and focus full-on in English lit. But 2.1 is fine for any employment purposes and having a language can be an immense plus-point from an employers perspective, dependant obviously for what kind of job you'd go for.
A language (rather than the fact you're doing joint honours) definitely enhances your employability, but then again so does a first (yes, yes, you only 'need' a 2.1, but a first helps you even more). It would really depend on which job you apply for.
Stick with the Spanish. If it drags down your overall mark, you can always put - say - "I got 72% for English, and 65% for Spanish" (or words to that effect) on your CV.
And I mean, at the end of the day, the majority of employers are either going to look at your degree transcript (in which case your performance in individual modules is more important), or not at anything other than your CV, in which case you can disclose as much information as you want.