I need to convert my Inkscape files to .tiff - how can this be done? Apologies for the complete lack of technical knowledge.

The export function only does .png (lossless) - You will have to open and convert to .tiff in another editor. Many editors have batch processing, so this is not as time consuming as it might sound. I like IrfanView for suchlike.

You can use 3-rd party solutions to convert svg to tiff, for example Altsoft Xml2PDF server