OP, sorry to put it bluntly, but if you're trying to hide things, you aren't fit to practice. I am not saying this issue would prevent you from practising or not, but your attitude is concerning and it cannot be justified by fear. You either know what you need to do and you do it or you don't.
Call the Law Society first for advice tomorrow. Speak to your firm's compliance officer. Even if it wasn't a restraining order, it could amount to a breach of code of conduct and therefore it may be notifiable.
I understand you had MH crisis back then, but there is no justification for letting this drag on for so long and for trying to wiggle out of it now. You should know that honesty is the best policy.
As for your comments that you were on maternity leave, how is this relevant? If you were employed and subject to SRA Code of Conduct maternity leave doesn't matter.
I am also concerned about the fact you didn't even investigate properly what has been issued to you after your MH improved. Words fail me sometimes.
Blunt words, but true. Don't be silly again, do the right thing, we don't have the full facts but purely on the limited information you gave, I would think it's not likely you'd end up struck off, but possibly with a lighter sanction.