I agree that the proceeds should go to a UK children's charity - however I ask that you choose carefully. As this is ebay UK, make sure the proceeds are split and distributed throughout the UK (England, Scotland, Wales, N. Ireland) or that when you pick national charities you pick ones that have a remit across the whole of the UK.

I work for the Scottish Council for Voluntary Organisations and it's a problem Scottish charities face - many of the well known 'national' charities such as RSPCA have no remit in Scotland and their Scottish counterparts (such as the SSPCA) lose out because people are not aware of this. Another example is the NSPCC who's Scottish sister-charity is Children 1st.