The bubbly little girl was diagnosed with spastic diplegia, a form of cerebral palsy at the age of two, which affects her mobility.
The life-changing surgery will eventually allow her to walk without the aids she has to use, including leg splints and a walker.
"We are on a countdown. We will be off at 6am tomorrow morning," said Annmaire.
"Myia will be going into hospital on Monday, when the pre-testing will be done, and she will be put on a fasting diet.
"Then she will have the operation, which could take around four hours, on Tuesday."
Annmarie said that Myia "is so excited she hasn't slept the past two nights".
Annmarie and her husband, John, have four other daughters: Shannon (9), Kayleigh (5), Laila (2) and Isabella (1).
Annmarie said it would be lovely if Myia was
home for January 29, when Laila turns three.
The family are delighted that the courageous seven-year-old is getting the operation done.
The selective dorsal rhizotomy (SDR) operation will increase Myia's balance.
The family only found out last month that the HSE was willing to fund the surgery, although fundraising is still required to raise the money required for Myia's aftercare.
"I can't describe it. It will be the start of a new life once all of this is done, even though I know it will take a long time," her mum said.
The final packing has been done for England, and Annmarie said that she has been stocking up on colouring books for Myia so she can pass the time while she is in hospital.
Myia will require aftercare for two years following the operation, including intensive physiotherapy five times a week for the first six months.
The local community has rallied around, with the AIB branch in Lucan recently raising another €500 through a coffee morning.
So far, fundraising efforts have succeeded in raising more than €17,000: a target of €26,000 has been set.
•Anybody wishing to donate can do so at the following account: Myia Corcoran, AIB Bank, SORT: 933562, ACC:27767013