Here’s a good thread for you and your dad to read : http://talk.collegeconfidential.com/prep-school-parents/1291390-unexpected-addl-bs-costs-besides-tuition-room-board-p1.html .
Have your dad call or email the NMH school business office and see what amount they recommend. Most parents start the year off by depositing $250.00- $500.00 in a student account and replenish it if needed . It’s up to your dad to set the weekly limit. If you need more cash for something special your dad can easily call/ email the business office and release more funds for that week. A student account is flexible and can be adjusted as you go.
The average BS student has a spending limit of $10.00- $20.00 a week . Most kids don’t even need that… and can get by easily with $5.00 or less. You won’t need a lot of cash at boarding school- especially if you’re allowed to charge your student account for items sold at the student bookstore or for snacks at the student café.
I think starting off with a $15.00 ( week ) limit is fair but do your dad a huge favor and manage it wisely. 