There is no right of first refusal for this type of dwelling under the CLR Act (Which you say you have looked). It only applies to flats leased individually.
With regards to your second question, this will depend on the terms of the lease. Because it is land there is not the same protection as for flat owners. Service charges are usually in connection with maintenance of a building, so I do not see that the landlord would be entitled unless he either builds the holiday home and maintains it, or it specifically states it in the lease.