My LA use a funding formula of £634.53 per annual TA hour. The 6k is 9.5 hours (ish) , plus £12700 is another 20 hours. 29.5 hours! However £634.54 hasn’t been updated recently to match current TA pay scales!
There may be extra costs with this child – our funding bands are 3, £6075 and 4 £9150, which is a full time ERS placement at our school. £12700 sounds like extra services or equipment may need to be bought in? Or maybe your LA are just more generous!