I live just an hour from The Lakes (as they're called - locally). I camp up there whenever I have the time, during the summer and have done so many campsites in the whole region.
You want just a simple one in a field.... I can help you there with 2 little beauties.
Hawkshead is a small village nestling close to the West Bank of Windermere and right on the edge Esthwaite Water. In the village are two wonderful pubs doing locally made ales and excellent home-cooked food, catering for all tastes. There is also an excellent little supermarket that sells everything (within reason) a camper needs for a satisfying self-prepared bitta grub. Just 10-15 minutes walk out of Hawkshead, up towards 'Hilltop' (Beatrix Potter's house), are two great campsites. Very basic, but just what you're looking for. They're both farms, the sites are just fields and little more - with very basic facilities, but have shower blocks, toilets and rubbish bins. There is a small road running alongside both sites, but if you pitch your tent at the bottom - you can't hear any traffic at all. The top site (just a few minutes walk further up the hill) even has a little dew pond at the end of the field that's normally about 5 - 6 feet deep in the middle and the farmer is more than happy for people to go bathing (of sorts!!) in it.
Incidentally, the road that runs alongside both sites is not very busy. It's only a single track with passing places.
Once you've eaten in the morning, take a trek, or the local bus ("The Mountain Goat") over to Tarn Hows. One of the most beautiful stretches of water in the National Park. There, you can walk round it, cook your lunch and swim all day without restrictions. There's a tiny island within it where I often swim to, with my lunch and a few beers tied on my back in a plastic bag too - and just forget that there's anything to worry about.
So that's the Hawkshead area.
Alternatively, how about Coniston Coppermines....
It's a fair old walk up to the mines (now disused), but the walk out of Coniston (check out Coniston Water closeby - tremendous stretch of water) up to it, is awesome. Just past the hostel is vast open land where it's OK to pitch a tent free of charge. Done it many times. The views are a photographer's dream.
Have a great 1.
