Address DB Split Into Multiple Territories Without Duplicate

I had a list of 1800 full addresses including Postcode on excel, I added 2 columns for Co-ordinates then one column that I use to input data when a call needs removing. I then imported to access table and started to use queries to sort our sales into territories of hopefully no more than 26 calls each, I used the spare column to input a R for removed then only list null entries in queries then I keep adding postcodes in the postcode criteria column until I get around 26 per Query.

My Ultimate goal is to Build multiple Tables of no more than 26 calls that I can geocode onto maps, to make it easier and more cost effective for our sales team.

My Problems are. How do I Prevent Duplicates when entering addresses if new address are entered, I Currently have access creating its own KeyI need to be able to track & prevent duplicate postcodes being assigned to more than one query/Territory table.I need either Access to either Produce a Table Report (As in excel) or might be easier if I just import my data back to excel table.

I kind of think I need new tables for Maps with relationships created between Map table and Territory table. but not sure if this is the best way to go or not.