Shiznit seems to have missed the point that you require an SD card with the maps on it, rather than a blank one.
Each manufacturer has their own mapping system, so you can't use a card from another make of satnav.
A borrowed Garmin card should work in Mr S's satnav but you won't be able to copy the data to another card. The maps have copy protection software built into them.
The only way to get a new SD card is to buy one for £33.99
https://buy.garmin.co...do?pID=8424&pvID=2595
Chris