In case you still need help, i have been answering claims for ash disruption for my airline. There is no template needed really. Just a letter saying you are claiming for out of pocket expenses for your enforced stay due to volcanic ash. Then you need to tell them:
Your name.
The name of anyone else travelling with you that you are claiming for (i,e partner, kids)
The flight details/date you were originally due home on.
The date and flight you did come back on
The number of nights you are claiming for accommodation, supported with the hotel bill (not just the credit card receipt).
Any food bills you are claiming, supported by the receipts.
Your bank details for processing the refund of your expenses.
An email address, and at least one phone number.
If you know what it is, it is always useful to include your flight booking reference.
If you include all that info, then it makes your claim ALOT quicker to deal with!!