Yes, there is a great chunk of North Somerset missing from the Ancestry 1851 census including Wraxall.
However, there is an index to it available from the Bristol & Avon FHS and Gordon Beavington's transcription includes it.
You mentioned HEDGES and and LANCASTER.
From Gordon Beavington's transcription
120
COLLINS Mary Wid/Widr 64 Parish Relief Som, St George
HEDGES Lucy Visitor 8 Scholar Wraxall
125
HEDGES Henry 29 Cordwainer Clevedon
Louisa 27 Midsummer Norton
Mark 7 Scholar Wraxall
Eliza 3 Scholar Wraxall
Page 33
HEDGES Frederick 7m Wraxall
PLOWS Thomas Lodger 24 Mason Middx
LANCASTER in Wraxall
107
LANCASTER Arthur 53 Haulier Nailsea
Pamela 51 Wraxall
Charlotte 18 Wraxall
Henry 16 Wraxall
George 11 Scholar Wraxall
Ellen 8 Scholar Wraxall
112
LANCASTER Mark 22 Ag. Lab Nailsea
Elizabeth 19 Wraxall.
Hope this helps a little
Pat