Looking for quiet, self contained room/flat/annex

I'm looking for a place to stay for 3 - 6 months or possibly longer if a good fit. Ideally a self contained place, or share with a quiet, mature householder. I work full time online as a therapeutic coach, so a peaceful, private, work from home space is essential. I would prefer to be close to accessing nature - lots of walks from the door would be ideal, and swimming would be a bonus too (leisure centre or wild swimming). I'm a quiet person, clean and tidy, very professional and will take good care of the place I stay. I travel a lot in my VW campervan at weekends, so ideally I need a place that has good safe off road parking for when I'm home.