I'm looking for a lightweight compact pram / stroller that folds up easily and is suitable from birth. Would need to be suitable for walks over the woods and on pavement, and available in the UK.
I would suggest the Cybex Mios as the most practical while really light and compact from-birth option. You can, but don't have to get a carrycot, you can also go for the seat insert cocoon for a newborn. The stroller will work on pavement well as even with the smaller wheels, it has a nice suspension and maneuverability. However, if you need a stroller for the woods (like, a forest road? not sure if I got you right), you can't think small and compact, a much bulkier and strudier option would be needed for that.
Just to have options, I will also mention the Joie Litetrax 4 as a simpler, more affordable though non-reversible option, the Valco Ultra Trend a s a super light urban choice with a great hood and the bootinet accessory for newborns, the Jane Muum V2 (not sure if available around you) that is full-featured but not too large, and the ABC Design Swing as a smaller pram/system.