This has been covered a lot already in previous posts. This is really unchartered water for BA. Just because they kept on temps in the past does not mean they will do it this time. There are a lot more factors now (eg: possible strike action, 900 hours, LGW joining NSP, etc).
If you were to do a temp EF contract, they could keep you on or send you to LGW, depending on where the vacancies are. If there are no vacancies, or you have run up your 900 hours, then they will not keep you on.
If you do a temp WW contract the same applies. The only way that you will be kept on at WW is if there are vacancies. These vacancies must be offered to the 100s of people on the transfer lists, so this will be highly unlikely - not impossible - but unlikely.