makes me think they would refuse again even if the tribunal insisted
They wouldn’t be able to do that.
DH reminded me the EHCP didn't have a setting so isn't final.
This isn’t necessarily the case. Section I of a draft must be blank. However, some finalised EHCPs also don’t have a placement named. Some will only have a type of placement and some will have section I blank. Definitely appeal as you can, but don’t rely on section I having a setting as the telltale sign of a finalised EHCPs.
If there is a possibility you will enter DS privately for Double Science &/or English Language, you should think about whether to do GCSE or IGCSE. For science and English Language, GCSE is harder to do as a private candidate because the practical statement and speaking endorsement respectively mean there are fewer centres who take private candidates for them. Centres are likely to become more cautious around this since Ofqual’s issued a Notice of Chief Regulator's Rebuke to WJEC earlier this year about 4 of their qualifications.
won't get EL3 let alone functional skills
Functional Skills come in different levels, including EL3 and both higher and lower levels. If EL3 is too much now, what about EL1 or EL2? If that is still too much, what about some of AQA UAS pre-entry level units?
English is tricky here too. DS1 won’t get an English qualification. IGCSE/GCSE English is beyond him. FS at any level doesn’t work for him either. Neither do other Entry Level Certificates.