Solution

36278

First name
Year 6
School
St Hilda's Bushey
Country
Age
10

We found 3 solutions by checking that it worked for all the envelopes:
they are, reading downwards

7 = 3,4 or 0,7 or 5,2
8 = 0,8 or 5,3 or 1,7
13 = 6,7 or 9,4 or 9,4
14 = 9,5 or 8,6 or 6,8
3 = 1,2 or 2,1 or 0,3