The index at
www.1837online.com gives this family, which looks like it could be yours.
PENNETT, Elizabeth 15 F North Aylesford
PENNETT, Joseph 54 M North Aylesford
PENNETT, Lucy E 57 F North Aylesford
I can't recall what the minimum spend is on that site, so maybe you could get the ref & image once you have some more people to look up.
The 1851 Kent, so far as I know has yet to be published on CD, so you may do best ordering it on film if you can. The nationarchives site gives this Census piece number:
Catalogue Reference Title/Scope and Content Covering Dates
HO 107/1609 Registration District: 52. NORTH AYLESFORD Registration Sub-District: 1 Northfleet ff.1-283 Parish: Northfleet 1851
HO 107/1609 Registration District: 52. NORTH AYLESFORD Registration Sub-District: 1 Northfleet ff.1-283 Parish: Ifield 1851
HO 107/1609 Registration District: 52. NORTH AYLESFORD Registration Sub-District: 1 Northfleet ff.1-283 Parish: Nursted 1851
HO 107/1609 Registration District: 52. NORTH AYLESFORD Registration Sub-District: 1 Northfleet ff.1-283 Parish: Meopham Hamlet: Culverstone Green (part) 1851
HO 107/1609 Registration District: 52. NORTH AYLESFORD Registration Sub-District: 1 Northfleet ff.1-283 Parish: Luddesdown 1851
HO 107/1609 Registration District: 52. NORTH AYLESFORD Registration Sub-District: 1 Northfleet ff.1-283 Parish: Cobham 1851
HO 107/1609 Registration District: 52. NORTH AYLESFORD Registration Sub-District: 1 Northfleet ff.1-283 Parish: Denton 1851
HO 107/1609 Registration District: 52. NORTH AYLESFORD Registration Sub-District: 1 Northfleet ff.1-283 Parish: Chalk 1851
HO 107/1609 Registration District: 52. NORTH AYLESFORD Registration Sub-District: 1 Northfleet ff.1-283 Parish: Shorne and Merston
Pauline