Doesn’t matter you can also claim it after baby is born so
My work said that I just needed to declare my maternity status by 15 weeks before. The matb1 form only needs to be given in latest a few weeks before you’re due to finish. Some workplaces might smush the two deadlines together for ease though, as ‘proof’ but you should be fine
I highly doubt they’ll make a problem over 2 weeks. I gave mine late too but had told my boss already.