42. For the purposes of ascertaining income other than grant income and loans treated as income in accordance with regulation 43 (treatment of student loans), any amounts intended for any expenditure specified in regulation 40(2) (determination of grant income), necessary as a result of his attendance on the course shall be disregarded but only if, and to the extent that, the necessary expenditure exceeds or is likely to exceed the amount of the sums disregarded under regulation 40(2) or (3) on like expenditure.