BIL and his family did this many years ago. They took about 18 months off. Oldest DC was in the middle of Year 5 (just after Christmas) when they left and they returned in the summer before he started in Year 7.
They rented out their house and lived on that income (they only had a small mortgage) and their savings.
The family seemed to enjoy it a lot and BIL and his wife are planning a repeat for when they retire (by themselves this time).
As to when to go, I would suggest either now or next year at the latest or instead wait until after A levels.
"...so I'm trying to negotiate a smaller time maybe 4-6 weeks just to give it a try."
That sounds a really excellent idea. There was a thread here recently about gap year travel and more than one poster recommended a company called "G Adventures". I know nothing about them myself:
https://www.mumsnet.com/talk/holidays/5049400-group-tours-abroad-for-older-teensstudents
Something like that might be a good suggestion. There are plenty of other tour companies that do similar 4-6 week holidays but for the more adventurous trips they are often adults only.
They are all also not cheap at all.
Although you can certainly find trips that are cheaper and where you are travelling by yourself. Just one example (there are many others out there if you search for them) is a company that do, amongst other things, Fly & Drive tours in China.
So you have an itinerary and a rental car for three or four weeks or however long you want. Eg starting from Chengdu spend three weeks driving through Sichuan and Yunnan.
You can also do these sort of fly & drive tours in many other countries and this may be a good way of starting.
"Or does anyone know of any blogs of people currently doing it?"
Yes, two. The first is an English family who have been doing this for years and have their own website:
https://travelynnfamily.com/
and a Canadian family that also have a lot of useful advice as well:
https://www.5losttogether.com/start-here/