Calculating the hours of sunlight exposure....

The place I feel could be a good grow spot is a miniature valley with very steep inclines, on both sides.
45% to 60% slopes (on much of the area), levelling out some towards the bottom, where a narrow, weak running stream snakes along the valley floor
and, at either side of the stream, boggy, marshland (where reeds grow and amphibians have been known to live) covers the most level ground.

At the top of both inclines there is farmland and/or walking trail pathways.
So the higher up the side, the easier to access BUT the more likelihood of discovery.

I will take a compass and find out the exact direction that both sides face.
I can also find out at what time the potential grow spots are exposed to sunlight
and at what time exposure ends.

BY FINDING OUT THESE FACTS IS IT POSSIBLE TO CALCULATE HOW MANY HOURS OF EXPOSURE TO THE SUN THESE SPOTS WILL RECIEVE DURING THE MONTHS OF APRIL to NOVEMBER???
All advise gratefully accepted

Yes. But do factor for cloudy days.

Doing what you need to do: survey! More light the better = bigger buds

Yes...there are many sites that give a fair representation of expected solar hours for a given location, even better is to goola earth, you zone, just like your local rozzers, in winter early spring and with great success in locating grows, then 6 months later,a bust, ... until the dutch come up with a specific strain that can grow in 50% less light and is impervious to mold, I'd grow indoors or even a shed under lights, should I be located in the UK

You should be looking for light hours from end of may to end Oct... There aren't enough light hours in April to keep your plants in veg so they will begin to flower... I read your other thread and saw you mentioned it will be your first grow so thought I'd point that out. It's a common rookie mistake outdoors. If you can find a farmer's almanac for your area it will give you exact daylight hours For any given time of year. Keep in mind as well that if you grow in a deep gully such as the one you describe, depending on the direction of the slopes you may only receive 4-5 hours of sunlight per day and it would likely be mud day when the sun is hottest. This could be problematic depending on how hot it gets there. If it's too hot during your sunny times your plants won't utilize the sun as well as they would if they received direct sun in a cooler part of the day. Hope this helps

Also... If your gully runs east to west and follows the suns path you will receive more light than if it runs north to south... You may want to see if your spot gets sun this time of year when the sun is at it's lowest. It's a good bet that if it receives Sun for 4-5 hours this time of year that during your growing season it will receive double that amount when it's at it's highest in summer

I don't think the local cops spend too much time on the hunt for outdoor plants.
It's far from usual in the UK and it's not a police priority.

I want to plant about 8 seedlings - but give them the best chance they could have.
The 8 would be 2 each of 4 different strains.
Say....
2 Durban
2 Mazar
2 Chitrali
2 Nepal
(that's just hypothetical).

If all 8 do rubbish - next year I will try different strains, different techniques. different locations.....

But, if the 2 Mazar do really good
and one of the Durban does OK
Next year I would try to find places for a minimum of 10 Mazar
and I would experiment a little with the Durban
(say 2 plants in 2 spots - Total of 4).

It's just something I wish to try.
To be perfectly honest, when I see the pictures of outdoor grows in the USA
I am greener than the plants (with envy!).
It must be a wonderful feeling of achievement to raise them on the resources that are mostly available through nature
(just add a few extras and put in the care and work....).

I would recommend frisian dew for your area. If you are doing seeds you should go with feminised so you don't end up wasting time on males. I did frisian dew last year and it yields large, mold and pest resistant and finishes early with tons of crystal frosting... They turn a nice purple near finish and look amazing