I wasn't aware that Langley has created an inner catchment area. Is it a draft in consultation or finalised version?
OP, since you live in the inner catchment does your DS just have to pass to get in? If so, it is a good deal for you. Living in SL3 you probably are in the catchment of other Slough in addition to Langley. You may also be in catchment of Burnham Grammar.
These are the SL post codes in Reading Boys catchment -
SL5 0, SL5 7, SL5 8 & SL5 9
SL6 1, SL6 2, SL6 3, SL6 4, SL6 5, SL6 6 & SL6 7
This is the link - http://www.reading-school.co.uk/98/designated-area
Langley outer catchment may cover SL5 and SL6 areas. Are you willing to move to those areas?
This year Bucks schools allocations have gone a long way. Which Bucks schools are you interested in?