Yep sure can! What you do is create a Parameter (down the bottom left hand corner) called AxisMetric or something similar. Create it as a string with 3 available options, Age Range, Membership Type, Newsletter, etc.
Then Create a calculated field called AxisMeasure. This field should be:
IF ([AxisMetric] = 'Age Range' then [AgeRange]
ELSEIF ([AxisMetric] = 'Membership Type' then [MembershipType]
ELSEIF ([AxisMetric] = 'Newsletter' then [Newsletter] else null end
Ensure you change the  parts to match your real measure names.
Then put this calculated field on your row or column shelf to add it to your worksheet. Right click the parameter and add to the sheet and you're ready to go.
Thanks a bunch for the quick reply Nathan! This worked a treat
I haven't got everything figured out yet, but I'm loving it