As Peter says, the correct mat is just as important as the right bag. If you need comfort (and an old fart like me does) then you can't beat Exped downmats.
As for bags, I am a big fan of Cumulus (now re-branded to Criterion, I see) and have the Quantum 200 for most 3-season backpacking and the Quantum 350 for when it's a bit colder. I've also got a PHD winter bag.
Criterion does not get mentioned much on here but they are top quality bags. I like the fact that they have full-length zips for temperature regulation and a differential fill. They are also very light - 530g for the 200, which is good down to 0C with a silk base layer and 695g for the 350, which will allegedly cope with -6C, although I haven't tested it at that temperature.
Sorry this thread isn't going as you expected, OP but, as others have pointed out, the reason wildcamping is broadly tolerated in England and Wales is because you have to put in a bit of effort to get to the good places off the beaten track. This means that wild campers tend to value the experience and take a bit of care not to leave rubbish and light fires etc.
Allow camping anywhere and every idle chav with access to a car will be trashing the countryside within months. As others have said, have a look at what has happened around the lochs in Scotland - they have had to actually (re)ban wild camping on the east shore of Loch Lomond because of thoughtless scrotes ruining it for everyone else.
I've been subscribed to TGO via iPad for some months. It works well but the latest issue has a problem with the photographs. They look fine at 100% size but as soon as you zoom in, the colours change, becoming over-saturated with a loss of definition. This hasn't happened with previous editions and is nothing to do with software as I've gone back and checked.