Try Seax-Essex archives, log on, pay £5 for 24 hours of viewing-Pentlow is on a digital format so you can search online for it. I would like to copy and past the online reference but the copyright system on Rootschat wont let me do it!
Go to Seax, Essex archives online, click on Essex ancestors, parish records online, put in Pentlow and search form there. I did a few searches on there and found all manner of information, £5 it's less that the cost of the train fare to Chelmsford.
Tom