I know this area well. For a 1.15 hr commute you are really pushing it with Suffolk. Your absolute top stretch would be Ipswich station, they do lots of fast trains
but unless you want to live in Ipswich central, which by the sounds of things you don't, DH will still have a 10-20 minute drive to any of the nicer villages on the outskirts.
Woodbridge is fabulous but really not doable - don't go there because you will fall in love and think you can do it, but DH will be miserable. just visit it at weekends instead.
Hadleigh in Suffolk is a really lovely place to live and is a fairly straightforward drive to Ipswich station but not a short one, and that road can be a bit treacherous at busy times and is often full of thundering lorries.
My DH also works long hours in London and I would not recommend that you get rose tinted about how manageable some of these longer commute would be. It can be gruelling, especially in winter.
I think you would be ok looking at Manningtree station and surrounding villages and that is undoubtedly a beautiful area.
Sudbury is more tricky. He'd have to get the branch line into Marks Tey before he can get on the main line to London, which is a total pain. Always remember that you have to factor in the drive in all weathers from whichever village you choose to the nearest station.
There are lots of lovely areas within easy reach of Marks Tey station, along the road through Fordstreet to the Colnes, Bures etc. Or the other side of the A12 from the station, Copford Green, Messing, etc, all lovely.
The villages north and east of Colchester are lovely. Look at places like Stoke By Nayland and Horkseley. They all hover on the Essex Suffolk border. West Bergholt is really nice and very handy for Colchester North station. But it's more a large cluster of lovely roads and lovely houses that is attached to Colchester itself rather than a separate functioning village with its own facilities. Also being much closer to Colchester town centre may or may not be a good thing - depends on what you want.
I would also recommend highly recommend Coggeshall and the surrounding area, for which you would use Kelvedon station which is two stations closer to London than Colchester.
Most parts of north Essex and the Essex/Suffolk border are so nice I could be recommending individual villages all day but I'd say with a few dodgy exceptions you can pretty much look anywhere that is within a 15 minute drive of any station from Kelvedon to Manningtree, with Ipswich at a push.
£900k should get you something really lovely.
If you want to keep the commute more sensible but still get that countryside feeling I would also recommend you look at the villages a short drive from Hatfield Peverel and Witham but prices do go up quite a bit there.
Terling is beautiful, as is Wickham Bishops and Little Braxted. You could even or look at going to Danbury or Little Baddow from Chelmsford station. All these areas are very highly desirable and very pretty.
Be warned though, I don't know what you think the average Brexiteer looks like, but both semi Rural Essex and Suffolk is positively heaving with wealthy, well educated Brexiteers. I am one. I am also a really nice, civilised person, a welcoming neighbour and good open minded friend to have, regardless of where you are from, and in all of the areas I mentioned, so will most other people be. As I imagine would be the case in the more affluent parts of Devon or Cornwall or almost any area that is predominantly semi rural or provincial.
If you are the kind of person who makes over-simplistic value judgements a person based on whether they voted in or out then you would probably feel more comfortable staying in your smug London bubble of righteousness. 