What you want to do is certainly possible. What you'll likely need to do is create a table just for the imported data. It can be a duplicate of the Nominations table (with unnecessary bits stripped out, if you like). Then, create a relationship between NominationsImport and People, based on the two fields FirstName and LastName. This will establish which records exist - or not - in People.
At this point, you can Find all the records in NominationsImport that don't have a match in People just by doing a Find on any related field in People and selecting Omit (the UUID is a good choice). Import those records to People.
Big, large, huge, ginormous caution here: Doing a relational match on first and last name is very, very risky. Duplicates are quite common. (How many "Bob Smiths" and "Jane Browns" have there been in the last 50 years?) You can somewhat mitigate it by comparing other data, like street address or phone, but I would recommend you see if there's a way to get a unique key of some sort on the incoming data to prevent missing one who's a name duplicate, but not actually the same person.
You have no idea how much that has help Mike, thank you!!
Yes you are right about the First Name and Last Name matches because it also matters when the spelling is different. Or we have a Mike or Michael, Matt or Matthew etc. For now I will go ahead just to get the first lot of info in there and then once it becomes a yearly process I will change it to Last Name and DOB.