Hi,
A copy of William and Eliza's marriage certificate should give the name and occupation of his father; using that information you could search for him in the census, which should show him with his parents.
The name and occupation of Eliza's father should also be on the certificate.
This looks like them:
Marriages (from FreeBMD):
William Loveless SepQ 1868 Dorchester 5a 593
possible bride: Eliza Jane Shiner.
Certificates cost £7 and can be ordered online at
http://www.gro.gov.ukNanny Jan