Hi, Do you mean you are living in the North East - so looking for a Grammar school in your area? Or are you leaving the North East and looking to move somewhere else with grammar schools?
Either way so you need to look at individual schools admission policies in the area you want- most will have an in year admission policy and not have a specific 13+ entry system. I think Buckinghamshire has some 12 + entry. The North East is a big area so might help to narrow it down a bit but I am not sure of any Grammar schools in that area. There are some in Lincolnshire, Yorkshire, Lancashire and Cumbria.
This might help you find schools and there is a menu of counties down the left side you can find individual schools.http://www.elevenplusexams.co.uk/school ... active-map
I am not sure you will get more of a definitive answer to your question. It is down to whoever else is on the forum and what they choose to share.....There is a lot of information to be found on this website so you may find your answers using the search function looking for 12+ entry/ In year admissions or something similar. There may also be the issue that the school is full and so you may need to appeal to get a place so have a read through the appeals process on this forum too.