Hi Jen.
My interest in the name Portch comes from Edith Lydbury, who married Thomas Portch on 7 July 1824 at Nunney. They had a son Thomas, who was born before their marriage, and was baptised Lydbury, but alternated between the surnames Lydbury and Portch all of his life.
From correspondance with another Portch researcher, sadly now deceased, it seems that the Thomas who married Edith was the half brother of Giles Portch of Sharpshaw Farm. (Giles married Hester West in 1829). Their father, also Giles Portch married twice, firstly to Martha Eatel 14 Feb. 1778, and secondly to Susanna Williams 4 Apr. 1794. Thomas was the son of the first marriage, and Giles was the son of the second.
There is a reference under the Bradford-On-Avon, Wilts. Independant baptisms (Morgans Hill) 1778-1837 , 26 Dec. 1779 Thomas Portch (born 1 Dec. 1779) son of Giles and Martha Portch. Also under Bradford-On-Avon Wilts. Countess of Huntingdon's Connexion Baptisms 1794-1838, 9 July 1797 Giles Portch (born 12 Apr 1797) son of Giles and Susanna . My correspondant told me that it was possible that the elder Giles was baptised at a Lady Huntingdon Chapel, which used Anglican Services and clergy, without being part of the Established Church, and although there was such a Chapel in Bradford, it's records do not begin soon enough for Giles. He says that it is probable that his parents were George Portch and Ann Self(e) married at Bradford 12 Jan. 1744, but it has not been confirmed.
None of the above has been verified by me personally, but it gives you a definite starting point. It also appears that Edwin Portch was the son of Giles Portch and Hester West, and so my Thomas was his uncle. Hope some of this is of interest.
Dale