If you want to fly, then fly - great job as a WSO, but do you really want to sit in the backseat if flying itself is your passion...
Regarding the eyesight test - you won't find out truly until you apply - what is reported by your high street optician needs to be verified and tested by the RAF. Apply (for pilot, WSO second), and see where you get to. The worst that could happen could be 2 years on the UAS before a civilian career instead...