Hi, I'm a part of the Manchester access programme (for university of Manchester) and through this I get to talk to optom lecturers and the admissions team, it's actually very common for people to put optometry as their second option after medicine / dentistry and they still get in. You can very easily make the work experience apply to optometry, they look for experience in healthcare (so they know you've got both the grades and human interaction) but it wouldn't hurt emailing some opticians and asking for a week / 2 weeks worth of work experience. I currently do one day a week for 2 months. A tip is to ask independent practices as they're more likely to give you it. Good luck!