This is very impressive and difficult to maintain in London. Rent for a "double" room - meaning a room in a flat/apartment or house that fits a US full or European double bed is like 900/month right now. Spending only 1200/month is very difficult to achieve. I have no idea how this is feasible. To add to rent, local stores are usually more expensive than the supermarkets.
Maybe you ought to make a masterclass on this topic.
If you took out mortgage when interest rates were really low, it’s possible to have your own place and spend about that much per month if you live frugally (well at least until you need to remortgage in few years and rates might be much higher). If you are renting though I also finding it difficult to believe. I was spending around 1600 pounds per month and I was living very modest live, spending little and trying to save as much of my income as I could.
Well my rent is only £600/month which helps a lot. It's in a less popular neighbourhood, but it's still in Zone 2 with good transport links and it's very nice.
Maybe you ought to make a masterclass on this topic.