Coffee whipped cream filling I want to make a coffee cream filling for a mocha roll cake. If I dissolve instant coffee into heavy cream will it cause cream to not whip up properly?
You should be fine, but you may have difficulties dissolving the instant coffee in cold cream. 

Let me suggest a tiny tweak:
Dissolve the instant coffee in a tablespoon or two of boiling water, let it cool until at least room temperature (or even refrigerator temperature) and add it to your semi-whipped cream. 

If you use a cream with a sufficiently high fat content - 35% or even 40% - the additional water will not cause any problems with whipping the cream properly. The lower the fat content of your cream or cream-and-other-liquid-mix, the harder it is to whip. Try to stay above 30% and chill your cream and the bowl well. Your heavy cream should be absolutely fine.