Hi Robert,
You are correct, Yeovilton Model Show is this weekend. On Saturday only though, entry for exhibitors from 7.30, general public from 10am. For those that don't know it, it's held at the RN Air Museum, just off the A303, and north of Yeovil itself. Not a bad show, all static, and a bit pricey, but you do get to go round the museum as well, the stands for models are in between the aircraft displays!
Danny