Contractual maternity pay 🤔

S 🌻 • Mother of one, engaged to my bestie of 10 years 💕

So I'm currently receiving contractual maternity pay, but am considering not returning to work. I've been advised by previous colleagues that I am supposed to pay this back if I decide to leave, however I haven't signed anything stating I will pay it back (I was supposed to but my manager is useless and forgot). I'm wondering, can they enforce this? Has anybody gone through something similar?