deposit protected but tenant didn't sign prescribed info

Hi,
I am quite new to being a landlord.
I recently took on a tenant and she was very friendly etc initially.
however has recently stop paying rent and is now no longer paying rent.
currently over 2 months due on a monthly basis so I am looking to go down the section 8 route.
I protected her deposit as soon as she paid in full (paid in instalments)
However, after attempting to meet to serve the prescribed info, she was unavailable, said she was in hospital.
since then after she stopped paying rent I have been continually trying to meet with her to discuss sorting things out, always politely, but she is basically avoiding any contact face to face contact, and will only sporadically reply to emails, but never agreeing to meet.
Eventually, I lost patience and posted two copies of the cert and asked her to return one signed. I never recieved my copy.

Now, if I go down the section 8 route and it goes to court what are the chances of her saying she didn't sign the certificate, or recieve he cert at all.

I have proof of the protected deposit (mydeposits.com) and I confirmed via email that I had protected the deposit etc, but she didn't reply.

Where do I stand?

Many thanks for any help!
regards,
J