I think you might need to clarify the Racel variable on your questionnaire. It states in your questionnaire that it is the Census question and it is but it is the census question used in England and Wales. There are different questions used in Scotland and Northern Ireland. So this variable could be used unknowingly to produce UK figures for ethnicity.
For example, as government researchers we use the harmonised standards which have to take into account the requirements of constituent countries when collecting and presenting data. For Northern Ireland, there should not be a ‘White British’ option as a specific requirement of the Good Friday Agreement is that people should not have to choose between 'Northern Irish/British and Irish identities and Irish'. In this instance it would seem that Racelt would be the most appropriate for the UK for ethnicity. It might be useful to have something in your guidance to make users aware of this.