NNEB is a very old qualification, are you aware of that? It was scrapped before I did my CACHE Diploma in Childcare and Education in 2001-3. This was the successor to NNEB. So her training was done before 2000- not that I would have any issue with a nanny who trained that long ago, but if this is her only qualification it seems she hasn't updated. There is a reason the qualification was scrapped, as was the one I did- society and the law moves on, big changes have occurred since her training.
You say she has life support training- I would check hard when it was done and how long the course was. If you want her to become registered to receive vouchers (illegal anyway in her own home) she would need to have an up to date paediactric first aid course of at least 6 hours for a nanny, 12 for a childminder. The certificate lasts 3 years so if it older than that then her training is out of date and worthless.
Caring for your child in her own home whilst not a registered child minder is illegal. Regardless of how lovely she is and whether she has done this before it is illegal for her to provide childcarer in her own home without being registered as a childminder. There are reasons for this! What would happen if something happened to your DD? Is this lady insured to care for children?
Childminders go through a long process to show they are up to the standards set by law- the house/flat is checked, they have policies in place for SEN, risk assessments, they provide an education. Nannies are employees and work in your home, and you employ them in a way any company would, paying tax, NI, employers NI.
I'd think long and hard about whether you really want to break the law, however lovely she is.