yes i believe you need to have done your tax return for 07/08 in order to receive this lump sum. i think you have until june 30th to do it though, if you can spare about half an hour try doing it yourself, otherwise ring up a small tax accountant and it might cost you about 100-150 dollars to get done.

as for the mods, id leave out the rotors if they dont NEED to be done and just got some new pads and dot5 fluid. then go with the rest of the stuff you mentioned eg braces.