I am a Holland Park parent. It is probably one of the better ones of the selection you mentioned. I will go through them...
Lady Margaret - very nice, know girls there - very happy, difficult to get into.
Hurlingham and Chelsea - sadly the local sink school no-one wants
Fulham Cross - up and coming, worth going to see
St Thomas More - nice school but you have to be a practising Roman Catholic and your child must be baptised (not as strict catholic criteria as others)
Sion Manning - used to be the sink school of Ladbroke Grove but now OK, Roman Catholic but generally easier to get into (perhaps check the distance of the last successful applicant last year). Academic results are not great but improving.
Chelsea Academy - unless you are CofE and worship in the Kensington Deaneries, very little chance (but depends how close you are). Also possible music aptitude route. School seems ok but the behaviour of the kids is quite bad and it has the lowest achieving kids in the Borough along with Sion Manning.
Holland Park - you are likely to be too far but perhaps try the art aptitude route which does not take distance into account.
Kensington Aldridge - you may be too far away. It was built to absorb the north Kensington kids and other local areas. The school only opened this week so an unknown.
Pimlico - no personal knowledge but a poster on the greycoats thread describes it as popular and up and coming.