The FIrst interview was very general relaxed questions. Including: Why the company? Why the role? Questions on your cv, like projects you have done and stated in more detail. The second interview was slightly more technically. Was asked basic data visualisation questions like whats wrong with the graph, what's wrong with colour schemes on this chart and etc. Not technical at all, if you have done GSCE math you will be fine, just seems like they want to gage how you are as a person.
