The thing about side return extensions is that while they may be small enough for PD, you will need to address party wall issues. I’m of the view that if in doubt, get advice from local planners, could save a lot of hassle in the long run!

Thanks Angie, I'm well aware I'll need a party wall award or some sort of contractual agreement with the neighbours for any of these options. Option two requiring two for the other side! Its option three that whilst I think is theoretical within PD, the gov UK documents aernt clear about extending past the original house. Its a small house so the bit that sticks out in 003 is what I'm curious about. Reason being is there is a manhole close and 003 means we wouldn't have to move the manhole, so whilst it's a slightly larger extension, it will same some money moving the drainage

I don't think Option 3 is allowed under PD as it goes beyond the boundary of the original house. Our neighbours had to re-submit as their patio doors were taking it something tiny like 2cm past the original house. You can get it with full planning permission though - we've done that as part of our planned extension.

Option 3 actually looks the best! Could be a great little space to tuck a pantry or utility cupboard into, also you could have a shaded area before entering the garden. Option 2 also looks lovely! That could give you a huge island with back to back cupboards. Any and all planning should really be looked at by either an architect or planner, they are always up to date with what is possible, best to do that, you may be pleasantly surprised!