Almost any small store has a microwave these days. Get one of those big coffee cups thats big enough to hold your bottle of pee. Stick the bottle in it, stop at store and put some coffee in it and nuke it for a couple seconds. That should be hot enough to get with in range. Practice doing it till you've got it figured out.
Still should be some hand warmers available at discount and sports stores. Generally they take about 45 minutes to get the bottle up to temp. Again experiment a little till you've got it right.