Hi Dianne ...
You're in luck - the Islip parish registers are included on the IGI (International Genealogical Index )!
You said that you're a "newbie", so this is what you do (my apologies if you already know this).
Go to
www.familysearch.org, click on "Search", then "International Genealogical Index".
Fill in one of the following batch numbers in the box indicated (near the bottom of the page):
J131511 - Baptisms 1590/1813
K131511 - Baptisms 1590/1813
C131512 - Baptisms 1813/1875
M131511 - Marriages 1590/1817
M131512 - Marriages 1813/1885
plus name and any other information you have, and see what comes up! (I'm not being unhelpful, but it really is more fun if you have a look for yourself!)
See how you get on ... then get back to us for some more help.
Pennie