I live on the Kent/Sussex border and know a reasonable amount about schools in the Tunbridge Wells area, down to Uckfield/Heathfield and out to East Grinstead.
Firstly, if you're at all unsure whether your DCs will pass 11+ (and it is increasingly competitive in West Kent with 2 out of the 3 boys grammars being super-selective ie only score and not distance) then I would opt for East Sussex. Uplands in Crowborough, Uckfield Community College and Heathfield Community College are all very good comprehensives. In addition, Beacon Community College in Crowborough is a vastly improving school and, with the increasing competitiveness of getting places at grammar schools in Tunbridge Wells is now gaining a lot of children who would have previously gone to TW.
TBH I'd avoid Sevenoaks as they have a very poorly regarded non-selective secondary and also problems with children from Sevenoaks not getting places in Tunbridge Wells grammars due to distance - they have no grammar schools in Sevenoaks itself.
Primary places in Tunbridge Wells are scarce, especially in the schools that are perceived to be "better". You would have more success in the outlying areas and village schools, for example Crowborough, Uckfield, Heathfield or Wadhurst.
I can't comment specifically on special needs but the school my elder child went to (Hartfield CE Primary) had a reputation as being a good school for children with SEN. However the head is leaving at Easter so changes are inevitable. Other primaries to look at in the East Sussex area that I have good reports of are St Thomas's in Groombridge (but usually full) and St Michael's in Withyham. Crowborough has good primaries as does Uckfield.
Hope this is of some help.