I would definitely recommend adding the creative writing but I'm a bit biased as that side of things is the reason for my degree. 
I've recently fallen into editing, originally to help out a friend who self-publishes but I love doing it and figured finishing off my degree would really help out as it's expanded recently into helping another friend with stage and screenwriting, she had the possibility to work with the BBC so I was basically learning on the job with helping her type and edit her script so when that's something they do in the advanced creative writing I thought that would help me out with expanding my work and I might even have the chance to write my own things with contacts I make there too.
The first creative writing course I did way back in 2011 and that's the course I've made the most friends through.
I chose A335 over A334 (both are level 3) as I just thought the range of set books sounded more appealing to me but according to other people on the course A334 wasn't anything like this and was much better. Because I have to do the advanced creative writing as my other level 3 course it meant I had the choice of the two when people just doing English Lit had to do both, I do think adding creative writing gives you more opportunity to be picky with the other courses you do at level 2 and 3 since you have one writing course you have to do at each level.
My other courses were level 1 AA100 (the arts past and present) in 2008 which I don't think they do any more, then level 2 creative writing (A215) in 2011.
I had a long break until I decided to finish off my degree before it "timed out" (the two courses gave me a Cert HE but I have until October 2024 to complete enough courses to turn it into a degree).
So in 2020 I did A112 Cultures then in 2021 A233 Telling Stories: the novel and beyond. I really loved both of these courses although I'm actually getting better TMA results in A335 (literature in transition: from 1800 to the present) than I did in A233. We got the option to write our own fairy tale for one TMA in A233 and that's something I'd love to go back and tidy up and explore more later on too.
I decided to keep the advanced creative writing to last just because I was already in the mindset of academic writing and typing out references etc which I know we didn't have to do so much for A215 and it means I finish off the degree with a course I've been really looking forward to.
The choice can be confusing but any time there is a choice just look at the different courses they recommend and see which one speaks to you the most. If you already know and enjoy some of the novels or at least the authors mentioned then that definitely helps.
Is it A111 then A112 you're doing for level 1 at least? I got to choose between them when I needed another level 1 course when I restarted and I really loved A112 and surprised myself when I did well in the art history side of things as I was looking forward to that part the least.
The only thing I found with creative writing is that you do get a lot of egos around. The forums have changed since I did it but back then we were allowed to share our work and our scores with others and we caused so much chaos I think that's why the OU doesn't allow that to happen now. 
But we had people saying stuff like "I've published 5 novels, and I only got 65 and I know my tutor is unbelievably wrong, how did you get distinction for this piece of drivel compared to me?" I had it myself when we were sharing what we had done for the EMA (just our ideas, not the actual written pieces) and I literally said "I've written a reworking of Shakespeare's As You Like It set in a medieval fantasy setting instead" then described my plot. Someone (mansplained) to me that my plot was exactly the same as Shakespeare's As You Like It. 🤦🏻♀️ A lot of people slated me for it and said there was no way I would pass. Whoever marked my paper thankfully thought differently and I got a mark I was very happy with. I actually got really high marks for the idea despite what my fellow students said.
I did learn to avoid those people though, most people are lovely on it and I'm hoping since we can't share our work the same way now it'll curb some of the egos. Fingers crossed anyway.
And apologies because this is incredibly long now so I'll stop there.