when you say easy walk, thats difficult to judge based on your fitness, experience, etc.
secluded away from the trails usually means climbing a hill, the higher the better,
the peak district is easily reachable, you could even go on the train from manchester piccadilly, but sadly it is a very popular place, and secluded away from the trails is difficult to achieve, you could camp on kinder but its a climb, and if your unfit it would be a challenge carrying camping gear.
even in the lake district, when me and Ape' pitch our tent on some of the less popular fells, thinking theres nobody around, a runner will appear out of nowhere just before dark, and surprise us.
the lake district does offer some great wild camping and stunning views, you only have to check out some of Aprils trip reports here on the forum,
however,
to have a relatively easy walk for 60-90 minutes, and reach somewhere secluded away from the trails for you to pitch your tent overnight to enjoy the peace and quiet and nature away from other folks is unrealistic to be honest, styhead tarn is an easy camping place but very popular, its the sort of place where we would avoid for this reason,
Snowdonia is another place, but ive not much experience wild camping here,
other folk may give you the benefit of their knowledge
good luck