Cheap PPL(H)
Those hours are the minimums that you must have together with a total of 45 hours in order to get your licence.
If there were no minimum hours required for areas like cross country, solo etc then you could hammer around the circuit for 45 hours.
As for paying the solo rate when you are flying as a solo student then yes your instructor is required to be available on the ground the whole time you are flying so you will pay the dual rate.
If you are trying to budget for your flying training then remember 45 hours is the minimum. If you budget that figure to get your licence then you may be dissapointed.