Hi Markey
Somehow strikes me as bizarre that someone from Scotland is giving you directions in the USA here but I suppose that's what happens when we all visit Florida on a regular basis.
Take Route 528 from MCO and then take the Sand Lake Road off-ramp. If you head along here you'll come across a Wal-Mart on your left at a junction (I think with John Young Parkway).
Alternatively, there's a small Walgreens on I-Drive straight across from WnW very close to Universal.
Garry