I am very sorry that you are missing your friends and do not feel 'at home' where you are living. There are two things that jump out at my, from your post. I have hesitated to post them, because I do not think it will be what you want to hear. I came back to this post incase it may in the longer term be useful for you, s9 here goes.
Firstly, a new baby is a big lifestyle change. It is very easy to confuse the changes in your lifestyle associated with a new stage in your life, with just being in another country. You will possibly have much more in common with new parents where you live now, and across the world, than with young, carefree people out 'on the town' in London (or any other place). For your own peace of mind, avoid using geography to explain how you are feeling. There are loads of sad, lonely people in London, and elsewhere. Isolation, loneliness, its a big part of the modern world for lots of people even if they have not moved countries
Secondly, while It is not easy for you, anyone who does not speak the language, and is not already in the process of learning the language, is not giving themselves a fair chance at feeling at home in a culture. I have lived in a (different) European country and can speak the language well enough to not be outed as a 'foreigner'. The kind of conversations i have with people who do not know my background are much more authentic, and hence interesting, than those I have with other people. You might like to give it a try, with the aim of talking to people without their having any idea of your differences, find the finds you have in common.
Once you have an extra-country relationship, the complication of where to live will always be there. Your best chance of happiness is to give it as little headspace as possible and avoid glamourising any other place.
All the best.