There are numerous family trees on Ancestry showing Sarah as having been baptised at Thanet in 1736 and having died in 1795. 1795 was the year of death of a Sarah Lucas in Thanet yet some family trees show 1795 without having married her off to William Lucas so I strongly suspect that people have copied other family trees without doing any checking. The trees with William Lucas show him as having been born and died at Thanet. I find it difficult to believe that William and Sarah would have both moved to London, remained there between 1765 and 1778 (at least) and then returned to Thanet after having their family.

While this is quite possible I think it more likely that William and Sarah were both Londoners. There are several possible baptisms of Sarah Holman in the London area and I think the one in 1751 at St John, Wapping is the most likely being close to where William & Sarah were married (St George in the East) and where most of their children were baptised. That would make Sarah's parents John & Jane but I cannot find a marriage for them. There is a marriage between John Homan (not Holman) and Jane Waller at St Botolph Aldgate on 26th May 1735 but I cannot find an image to check the details. However, it seems unlikely that this is the correct marriage as there are baptisms recorded as Homan between 1735 and 1751 and not all at Aldgate.