Given that most people don't complete their PPL in the minimum time required and that all experience is useful, then yes, go for it. Log the dual time with your instructor, ask the school to sign/stamp your logbook as a back up, but then when you're back in the UK simply carry on. The extra hours experience will certainly help you along even if none of it can be counted towards theJAR PPL issue (a daft rule if you ask me).
As an example, I used MS Flight Sim a lot before and during my IMC and then IR ratings. It really helped my scan rate and situational awareness despite none of it counting a bean for the ratings, it minimised the time I needed to spend learning.