I think you pays your money and takes your choice zac, though as a lifelong four-eyes, I agree entirely with daffy and boxy. On eye tests, I've never had the same level of service and quality from the chains as from an independent local - and properly qualified - opthalmologist.
Don't be fooled by the chain deals either. My current opticians always does a second pair half-price (imo you do need two and pairs on the go for both wear and tear and "where's my specs" moments) and they also have a great range of unbranded under twenty quid frames which I use for just for a change pairs. They've never charged me for running repairs either.
For frames, remember they're little machines for your face, so check how robust the hinges and nose pieces are, and invest a fiver in the little screwdriver and screw kits most opticians sell for keeping arms, frames and lenses attached.
And welcome to the Joy of Spex...