Check the charger availability in the city centre especially near the Marlands/WestQuay retail parks Multistory.
Plus pod point freebies at the Totton Asda or Bursledon Tesco.
Use ZAP-MAP either internet webpage, or their phone-app (or both ! )
It's a very clever tool both for finding where what charge are, and which schemes, and users comments.
Also check PlugShare for other comments about charger points, and to use to log your connection when you are using one .
Tell her to guard the keys carefully, you'll all love the nippiness of the Mii !