Day trip pitch up spots Bucks, Berks, Oxon

[Scooby19]

Hi,

We’ve recently bought an Ocean and and been away a few weekends, but also like to get away just for the day. Does anyone know a good place to search for day trip sites where we can just set up the awning and plot for the day, enjoying the view and a picnic....deally quiet countryside or riverside spots rather than just car parks .

Thanks for any advice