This from JSP 752 (sad, I know but in this day of JPA 'self-service' you have to know the rules....):
LOA is payable from (and including) the date of arrival in an LOA area up to and including the day before the date of departure from the area
and
The Temporary Assignment Rate of LOA is paid when Service personnel are temporarily on duty overseas; they need not have a Temporary Assignment Order (see paragraph 06.0122). The Temporary Assignment Rate of LOA is 75% of the S/MU Full Rate of LOA payable
It's about £10 a day for a Flt Lt.
I think LSA is subject to the >=10 days rule.
Cheers
SBG