You cant drive on the roads unless your eyesight meets certain requirements.
The easiest way to check this yourself is to try and read a number plate at the specified distance and if you cant you should visit a optician before you start.
The regulations state that, in good daylight you should be able to read a vehicle number plate with letters 79.4mm (or 3.1in) high at a minimum distance of 20.5 metres (around 67 feet)
If you need glasses or contact lenses to read the number plate that's fine.
However you must wear them whenever you drive. If you have had sight correction surgery you should declare this when you apply for your provisional licence.
In 2018 the DVSA will be allowing learner drivers onto motorways with a DVSA driving instructor in a vehicle fitted with dual controls ( the DVSA will be setting a date for when this will happen until then it will still be illegal to do so)