Reading last non-blank cell in each row at 3 column steps

I have rows of registered people using my charity and I record donations in a cell of their particular row, then calculated tax relief, then in the next column the donation date.

SMITH / ADDRESS etc / £50.00 / tax 12.50 / 07.09.2009 / NULL / NULL / NULL etc
JONES / ADDRESS etc / £20.00 / tax 5.00 / 01.09.2009 / £35.00 / tax 8.75 / 06.09.2009 / NULL / NULL / NULL / etc

I have a series of empty cells awaiting completion with this data as each person makes another donation.

I acknowledge each donation by letter in Word which accesses this data in Mailmerge.

I need to have a fixed reference cell at then end of each row, say at row ZZ which has a formula to identify the LATEST donation and insert the value of the donated sum on that date. The info in cell ZZ (latest donated sum) is inserted into the Word document.

I've thought about VLOOKUP, COUNT, etc but can't make these work in my head.

Any ideas please?