Ah, I moved out of London 7 months pregnant with DC1, it was a lot of change in a very short time frame (I can point quite clearly to the 6 months period in which I became a proper grown up!)
Is your DP still commuting into London? So have you picked an area that's commuter belt? In which case, you might find the bulk of the locals are also "London ex-pats" who'll repeat things like "we got a 4 bed house for the price of our old 2 bed flat in London" and "you don't have to fake being religious or find the money for prep to get a good school". You might start seeing just how lovely Boden and Fatface are. You might start coverting a Jules gilet.
The safety aspect is a bit different, that teenagers in hoodies making eye contact aren't about to rob you, they are trying to work out if you are one of their mum's friends.
If like me, you were used to seeing those "crime committed here" signs everywhere you went, and just it was a given that people did get stabbed within a mile of your house because it's London and that's just what happens, you will find the local news shockingly sweet. For instance, it made the front page of our local paper when the hanging basket of flowers outside the butchers was stolen.
Just make sure you go into London regularly. If it's commutable for work, then you can go for the day too, don't let "going up to town" become a big deal. (I have local friends here who think it's odd I went up to London to do my shopping, when it's 25 minutes to London bridge on a fast train, yet they'll drive to a shopping centre 30 minutes away and just go for a morning)