I am not an expert on making GA claims, but my understanding is that you will need to make a separate claim for each relevant accounting period. You do not say whether your church is regarded by HMRC as a trust, in which case it needs to make claims covering tax years, or as a corporate body, in which case recent claims need to be made for your financial year (previously you could claim for any period, including tax years).
You need to make separate claims each year because tax rates can (and have) changed. You will also need to use the "old" R68 forms for claims up to 5/4/08, and then the "new" forms for the last two years.
I suggest you read the detail at
http://www.hmrc.gov.uk/charities/guidance-notes/chapter6/parta.htm very carefully and apply it to your specific circumstances.