Referencing one column against two other columns to create Y or N

Hi everyone

If you open the attached spreadsheet, what I'm about to type makes more sense!

I am looking to do the following:

Whatever is entered in Column A2 to A5000 in workbook "Full participant list" (you have examples of Summer Writers and Ceramics in the spreadsheet), I want it to look at Column A in workbook "Surveys and ACE" to see if it finds an exact copy of this. If an exact match is found, I then want Excel to look at column K in the same workbook, and if the value is greater than 0.1, I want it to place a "Y" in Column T of "Full Participant list". I want to replicate this so after matching A2:A5000 in "Full participant list", it checks the same in Column A in workbook "Surveys and ACE" to see if it finds an exact copy of this, but then looks at Column L and adds a "Y" to Column U of "Full Participant list" if there's a value of more than 0.1.

I hope this makes sense when read against the Excel sheet I have attached. If not, please let me know and I will try and clarify further... assuming this can be done at all!

Thank you in advance for the help from the hive mind.

Best wishes

Iam