student_finance_calc.py

year = 2017
rpi = 0.02
inflation = 0.027778
maintance = 8570
start_fee = 9250

def loan(target, maint=maintance):
  return (start_fee * (1 + inflation) ** (target - year)) + maint


def total_fee(year, accum=0):
  return (accum + loan(year)) * (1 + rpi)
  
def total(start, end):
  accum = 0
  current_year = start
  while end+1 > current_year:
    accum = total_fee(current_year, accum)
    current_year += 1
  return accum

wipe = 30
salery = 40000
rate_increase = 0.05

def years(amount, start_salery=salery):
  y = 0
  pay_sum = 0
  while y < 30 and amount > 0:
    # Intrest
    amount += amount * inflation
    # Pay off
    pay_off = start_salery * 0.09
    pay_sum += pay_off
    amount -= pay_off
    start_salery += start_salery * rate_increase

    y+=1
    
  if amount < 0:
    amount = 0
  return y, amount, pay_sum

for i in range(4):
  start = 2017 + 4 * i
  end = start + 4
  print(str(start) + " - " + str(end))
  
  after_uni = total(start, end)
  print("Total debt after uni: " + str(after_uni))
  yy, amount, pay_sum = years(total(start, end))
  print("In " + str(yy))

9% is only paid on > £21000, so that should be subtracted from the salary value.