Only by testing, can you find out what different foods do to your blood glucose.
It's harder still if (as is only too common) you are given a prescription and no further advice.
"Eat a healthy diet" is not useful, since there isn't a concensus on what that is. Drop sugar is a good start.
Funding your own meter, at least for a couple of months isn't too costly. Try ringing one of the supply companiess, you may well get a meter free with a few test strips. My Meter is a Freestyle mini, supplied by Abbot diabetes care. It's easy to use and has a good instruction booklet.