It’s worth familiarising yourself with the national drone regulations to ensure you’re flying safely and legally:
UK Drone Laws: Where Can I Fly? | HELIGUY.com™
For example, your flight to a height of 150m was illegal as you’re restricted to a maximum of 120m. Also, there are further regulations about flying close to buildings and over built-up areas. Incidentally, 400m range in an urban area isn’t bad but remember that you can only fly it legally as far away as you can see it with the naked eye, unaided (except for glasses).
It’s worth getting the DroneAssist and UAV Forecast apps. DroneAssist shows you any flight restrictions in your area and UAV Forecast will give you a reasonable idea of the wind at different heights. The inability to fly home against the wind is probably the biggest single cause of lost Minis.