Charging to 100% is fine whenever you need it, it is recommended at least once a month to balance the battery.
The thing that ages a battery is time spent at 100% (or close to it), that's what you want to minimise - so don't leave it with a high state of charge. Rapid charging also has a wearing effect.
However, batteries last so well that it won't really affect you unless you plan to keep the car for 10 years and go well around the clock. All the models should be good for 200,000 miles with a decent battery life left.
Also make sure she has:
- ECO mode on
- Energy saving on in ECO mode
- ECO set on AC
- AC Temperature not too high and low fan speed
- Intelligent battery heating set to OFF
145 miles should be no trouble at all for a LR, minimum I get even driving hard in sport mode is around 180 miles.
50mph should give you around 4m/kWh or more, suggesting that something is not set right.
Finally, there's nothing wrong with getting home with 12%.