After messing around with the permalinks i have now found the cause of the problem. it was actually to do with with the categories themselves. I uploaded via csv file however the categories even though separated by a forward slash in the csv only created parent categories, with really long names.
The solution was to delete the old names on the categories and then put them in order in under the settings / menu tab so that parents and child categories exist.
Was going to delete this. but i have been searching for an answer all night it was only after trying on a local server with new install that my situation was not standard.
I should have noticed sooner.
Hope this helps someone out there and saves you a bit of time