After WDW, the Wal-Mart is the next best attraction!! Its huge and sells EVERYTHING.....from guns to bananas and everything else in between!! The toy section alone is about as big as our Tesco!
As Steph said, its crowded, sometimes dirty and the staff rarely speak anything other than Spanish, but I wouldnt miss it!! We dont buy food there, (Publix is better for that) but its great for souvenirs, coolers, swim wear, toys, bedding, fabric, office supplies cheap T shirts and shorts.....actually I cant think of anything they DONT sell!
The nearest to I-drive is Sandlake Road (the biggest junction on I-drive).....just go east on Sandlake Rd and you will see the Wal-Mart on the right after a couple of miles.
Happy shopping and safe driving!
Allie.
PS. Chances are there will be loads of Brits leaving the Car rental place at the same time as you, dont be shy, ask to follow someone going to I-drive to get yourself used to the driving.