Thank you for the replies. I have taken inspiration from a house nearby and really like the idea of a rear extension that opens up the back bedroom into a mezzanine area (which then becomes a home office / gym / laundry room. This requires the side extension to be of a higher height (~1.5 stories high) with a glass roof slanted towards the top of the mezzanine level. Given the back of our property is set down at a lower ground level than the neighbouring property by ~ 1.5 metres they will not be overlooked anymore than a regular 1 story side return. Do you think Lambeth will give planning for this kind of extension? bearing in mind we want to go back by 3m with a regular rear extension too. So it will essentially be a rear extension and side return (rather than a wraparound). The link to the photos of the house extension on the next street along that did this are here: https://www.zoopla.co.uk/property-history/8-northstead-road/london/sw2-3jw/18089869 The planning for this was granted back in 2004 so I can't find any docs related to it. Thanks fro your help!

Maybe just adding to the corner to take the porch width right across the back would help. By incorporating the porch area into the structure of the house it could give an informal dining area to the kitchen but also allow a travel within the home to be circular. I would consider a large slider or combination of slider and window to keep the outside wall letting in lots of light.

Thanks for taking the time Jonathan! Really appreciate it. My challenge was always how to make the best use of 'current' kitchen knowing we are keeping the pillar on the rear wall. The space is small and I settled on boxing it off and using some space for recessing 'new' kitchen pantry and F/F. I have been in houses where you walk through a longer hallway (old kitchen) with utility and loo left and right and it felt a little off. The extension will house the main family space for dining and work/ play (movies, study, work from home). The new kitchen will have a step down (150-200mm) into the extension. The front living room is effectively my husbands - for watching all the sport he loves. The room is East facing and cosy. There will be aluminium glazed partition/ French door (2400mm W x 2300mmH) from the front living room to kitchen in same colour as extension glazing - Reed Green. This is so the kitchen gets as much light as possible and the front room feels connected and not a room rarely used. I am second guessing myself. My husband completely trusts me so on here to see if further changes could be made to optimise.

Master bedroom with attached bathroom and dressing room Bedroom without bathroom Kitchen Commen̈ bathroom Dining room Living room Courtyard Pooja place in ground floor One bedroom with attached bathroom Hall Balcony Oppen terrace As per attached plot details