Speak to your EA area Fisheries Officer they can often lay their hands on surprising amounts of money especially if you have established good relations with them.
Ring the WTT or email
director@wildtrout.org if your project is a follow up from an Advisory Visit they might be able to assist with a rod from Orvis or Sage for a raffle or Auction prize (see Warren's sensible suggestion).
Are you in the Peak District National Park?
Your County Council may have a fund for environmental enhancement projects. As might the local Nature Trust.
What sort of amount are you after and what benefits to the environment and or wider community does your projct offer.
Whatever you do kep detailed records of your and other volunteers' time because you might be able to set it off as work in king against any grant aid.
Fell free to telephone me if I can help further
Regards
Rob
07976 926672