I'm glad the battery hasn't leaked yet, however it will in some time to come, could be tomorrow, could be next week, could be next year but it will so I suggest having someone remove it
You can use the card without the battery, the clock just wont keep time or you can replace with a coin battery.
The Simms are quite easy to get hold of, I probably have a spare one that I could sell you for a few quid +P&P
All the best.
Steve.