Hi Scully,
I've only been to Marcle Church once, St Bartholomews, and that for the Funeral of an old and close family friend, but I'm no expert on it's history.
However it looks very much like it is the Church your PRs refer to, assuming they were CofE, as it genuinely is an ancient Church and not just built to look old.
These sites all state it dates from the C13th, with some good history & photos. It's clearly a lovely Church with many beautiful old features to admire both inside and out, worth visiting on a quiet bright day !.
http://www.britannia.com/history/herefords/churches/muchmarcle.html
http://muchmarcle.net/st-bartholomews-church/#axzz24oER7pmy
http://churchdb.gukutils.org.uk/HEF150.php
http://www.wyenot.com/muchmarcle.htm
Sadly but in this day & age it may be worth contacting the Church in advance to check it will be open.
http://www.achurchnearyou.com/much-marcle-st-bartholomew/
It might help you to plan your visit, not to mention confirm you have the correct Church for sure, by buying the relevant cd for a plan/record of Marcle Church's Monumental Inscriptions.
http://www.herefordshirefhs.org.uk/publications
http://www.herefordshirefhs.org.uk/images/stories/downloads/mi_cd.pdf
"Much Marcle, C of E - St Bartholomew / Nonconformist 1994, HEF-P0307"