Hi Nigel
Apart from the whole day of ground school it sounds reasonable to me that you’d need to do some ground school and a minimum of 1 hours flying in the Longranger having only flown the Jetranger, how many hours ground school have the CAA said you have to do?
On the flying side your only talking an extra 20 minutes compared to the FAA system, also the times you’ve quoted are minimums you could end up flying longer at the discretion of the instructor/training school. This would apply to both FAA & CAA systems.
By the time you’ve started the machine, done a few circuits, confined area, limited power, vortex ring, few EOLs etc etc, your going to be into an hours flight time.
On the R44 comment the Astro and the hydraulic 1 & 2 are the same variant, as far as I remember. But I think most schools/instructors would insist on a familiarisation flight if changing between these variants.