I'm guessing its just one or two errors you've made?
If so it would be best to adjust manually as a journal. Then do a manual adjustment on the next vat return to correct the error.
This is so the reconciled vat return isn't affected & the accountant can still see the original submitted vat return & as you will have done journals (to code 2202) they can see what you have adjusted and why & attach the manual adjustment workings with your next vat return to show why the figures are different to the reconciled return on sage.