Since the UK government introduced this ridiculously high airport departure tax, especially for C and F tickets, I wanted to ask whether this routing would be permitted in order to minimize the ADT:

day 1: FRA-LHR arrive LHR at 9a.m. in C
day 2: LHR-TLV depart LHR at 8a.m. in F
day 6: TLV-LHR arrive LHR in F
day 9: LHR-FRA depart LHR in Y/C

1) Could anyone please confirm the stopover is permitted?
2) I won´t be charged the ADT on the outbound, as my connection in LHR is <24h, right?
3) I guess I´ll be charged the ADT (11GBP in Y / 22GBP in C for short-haul flights?) on my return due to the stopover?

Thank´s in advance!