Spend a day somewhere your phone cannot reach you
Plan a quiet day at Wicken Fen with the practical arrangements made and ordinary notifications put aside.

Choose to be unavailable
You do not need to find a valley with no reception to spend a day beyond the reach of notifications. You can decide, make the necessary arrangements and put the phone away. That is less romantic than disappearing into the wilderness, but rather easier to organise on a Saturday.
For a manageable version, try Wicken Fen in Cambridgeshire. The National Trust reserve offers a boardwalk, hides and open fenland to pay attention to. This is a suggestion for a deliberately quiet day, not a claim that mobile signals disappear there.
Choose a daytime visit, with enough time for a gentle walk, lunch and a sit. A book or a pair of binoculars gives your hands something to do during the first few occasions when they reach automatically for your pocket.
Arrange the ordinary things first
Check the National Trust visitor page for current opening times, admission, parking and notices. The historic Sedge Fen area, including the boardwalk, is entered through the visitor centre. Wider reserve routes are a different proposition; choose the route that suits your mobility, experience and the weather.
The access information describes level access to the visitor centre and boardwalk, alongside facilities and potential limitations. Ask the property about your particular needs rather than assuming that a flat landscape makes every path accessible.
Decide how you will get home. Save essential tickets and directions for offline use, or carry paper copies. Take water, food if needed and clothing for a change in weather. Check conditions before setting out, then ask staff about the day’s routes when you arrive.
Tell someone where you are going and when you expect to be back. If people depend on you, agree cover or a limited emergency contact arrangement. Being unavailable works better when it does not transfer a surprise problem to somebody else.
Put the phone away without throwing away its uses
Silence ordinary notifications and keep the charged phone accessible for navigation or an emergency. If you need urgent calls to get through, set up and test the relevant exception before leaving. A break can have a sensible boundary.
You are not attempting an endurance event in technological purity. Use the device if you need it. Then put it away again. The point is to stop every spare moment becoming an invitation to check something elsewhere.
Start with the boardwalk and a hide. Remain on permitted routes and give wildlife and grazing animals space. There is no requirement to identify everything. A bird can be interesting before you know its name; the movement of reeds can hold your attention without becoming content.
Give the day some slack
If you have planned lunch, eat it slowly. Read a few pages. Let the afternoon contain a period for which you have no particular output in mind.
You may feel restless. You may find yourself drafting a message in your head or wondering what you are missing. That does not mean the day has failed. It means the day is different from the one you usually have.
There is no promised reset waiting at the car park. There is simply the possibility of getting home with a few things in your head that you actually saw, rather than things a screen placed there. For one day, that is a worthwhile exchange.