Mat B1 form during covid

Hi, First time mum here, with very little knowledge of everything in terms of baby prepping, as we're some of the first in our close friendship circles to have kids.

Had my 20 week scan, got my 25 week appointment booked in 4 weeks, and it will be a phone appointment because of restrictions. According to everything I've read, by 25 weeks you need to have given maternity notice in writing to your employer WITH the Mat B1 form. All has been discussed with employer loosely since 13 weeks anyway.

I'm also working from home, so couldn't physically give it to my employer even if I could physically get it from my midwife.

How have other people received theirs?

How important is it to be able to provide it to the employer? Especially as my boss will have to advertise a secondment to cover my maternity leave quite soon.

Thanks in advance for the help?