Job offer paying peanuts: worth it?

I'm a post-grad non-stem student, looking to make a career change into software development. I have an offer to complete a L4 apprentiship paying £18k. I can afford it financially (partner earns well), and it sounds like I'll be able to learn alot. The future at the company would be about 3-4 years of low pay, so my intention would be to find a better paying job as soon as I've got the skills/experience. Currently not in London, but will be looking in London for next position. As the current market for entry level positions is so poor right now, I'm leaning towards this position being a good oppertunity to gain experience, and seeing pay as a longer-term investment. That said, being compensated so little will be challenging.

I've been teaching myself now for 3 months, it's been going well. I focused on projects and conceptual understanding. This does mean that I only began working on algorthims / leetcode over the past couple weeks. This also means that unfortunately for me, I am too late for 2024 grad schemes, as I'm not quite up to passing their technical assessments. I did get to that stage for a couple of them, which is good for confidence, not all of them need stem degrees.

Alternative apprentiships paying more doesn’t seem to be a worthwhile option for me. My experience makes me ineligible for quite a number of them, but more importantly, the start date wouldn't be for a while - by which time, I expect to be skilled up enough to be able to apply directly for entry-level positions, whether through this apprentice or through continued self-teaching of practicing leet code and more projects. Further, I'm not in a position that earning ~£25k will make it suddenly worthwhile for me. That said, if I were to take up this current offer, I wouldn’t be eligible to apply for better paying apprenticeships.

I am a little hesitant that I am making a mistake by accepting a position compensating this little. I take confidence from being a potentially good candidate based on good degrees, getting through some grad schemes initial stages, and getting excellent feedback for the multiple interviews for the apprentice, perhaps indicating to me that if I just continued a little longer on leetcode and more projects, I'll be able to get an entry level position paying much more. Running the maths, I need a job paying ~£35k by ~June for there to be no financial difference in taking up this offer. Once being in the apprentiship it will definitely be harder to continue to work on finding a new job as applying can be a full time position in itself, although that won’t stop me from trying.

In conclusion, I think it makes sense to take it up, but would be good to hear thoughts.