Finally got this sorted after a few hours of messing about...
1. export from dashlane as 'unsecured archive (readable) for Excel'
2. copy and paste columns into the template found at https://helpdesk.lastpass.com/wp-conten ... dsheet.csv
3. open the template with Notepad
4. from my vault click on more options > advanced > import and select 'Generic CSV file'
5. copy and paste from Notepad