Hi Angus,
I can confirm the baptisms of William (1804), Charlotte (1809), George (1811) & Charlotte (1813).
Source: Bristol Records Office (BRO), Temple BTs, 1812, Number 83.
Charlotte BENNETT, buried at Temple, Bristol, 21st May 1812, Child.
The ONLY Bristol marriage I can find for Isaac & Elizabeth BENNETT is as follows:-
An Isaac BENNETT married Elizabeth REXWORTHY at St Mary, Redcliffe, Bristol, 24th February 1799.
Victor