He works here so we'll be in two countries
You may have omitted one word in the above sentence, OP, but the meaning should be perfectly clear to all and I have no doubt that, after you have moved back to your family in Ireland, you and and your abusive h will be in two separate countries.
As your h has given his verbal consent to the child of your marriage accompanying you, and as time is now of the essence, I would suggest you write a letter with today's date on the following lines to The Director, Children's Services, at your local authority's address:
Dear SIr/Madam,
Subsequent to the incident on (date of incident) which resulted in my husband (his full name) being arrested by the police and charged with an offence against my person, it is my intention to live with my family at (your family's address) for the foreseeable future in order that I can benefit from their support during my current pregnancy.
In the course of a recent conversation with my father, (your father's name), my husband gave his consent for our child, (child's name), to accompany me and we will be leaving the UK on Friday 2 December 2016.
As I was given to understand by a member of your staff that I would be referred for a MARA I feel it is incumbent on me to inform you of my change of circumstances and apologise for any inconvenience this may have caused.
Yours faithfully,
signed by you
Make and keep a couple of copies of the letter and post it (by snail mail) either tomorrow evening or Friday morning.
Should your h choose to revert to type deny that he consented to you taking your dc out of the UK at some future date, the letter may go some way to establishing that you acted in good faith.