If you have not sold the car already, by all means check on webuyanycar, but dont sell to them.
Instead I would recommend using a site like Wizzle where lots of
dealers bid on the car and you are far more likely to get a higher price. I have used them many times and its be brilliant (typically I have achieved 5-10% above tradein/webuyany car).
It might also be worth touching base with your
dealer as most buying departments are desperate for cars at the moment as there is simply no stock on the forecourts.
Of course selling privately is how you may get the best price but lots of people dont like doing that.