Yes, if you have been offered a different term or loan amount by Nationwide, you can choose a new option and re-process your application to get a new result. You'll need to do this from your results page, in the same browsing session. 

If you do not pick one of these need options, you can choose to edit your original application and change your previously submitted details. Please bear in mind that this would be considered a new application by Nationwide, and a new soft credit check will be done.