SELT choices - is there a catch?

[SureShot]

So I see that "Trinity GECE Grade 5 B1" test is available for booking (and taking) it within 3-4 days.
While the "IELTS Life Skills B1" has availability only one month from now.

Does anyone know if there is a catch in this? Is the IELTS easier to pass or something like that.

Second question (which ideally should have been the first one) is - Do I need to get a SELT result even If my overseas qualification was previously on the calculator. I did not have to show anything while the initial application and the 2 extensions.

Thanks a lot.

Cheers.
SS