The requirement for an hour instructional flight disappeared some time ago. The regulation now requires a tolal of one hour flight time with an instructor and could be any number of flights with any number of instructors. This doesn't quite match the latest guidance material which suggests the content of the training should include those items normally covered in a proficiency check.
As this experience requirement is the same for a LAPL and UK PPL there is absolutely nothing to prohibit the same flights and hours counting towards both licences.