I take it the match is still on? I don't know about Cumbria but it has been raining heavily down here overnight and today, seems to be brightening up though now, in time for the big football matches.
I honestly think you can win that game today, I saw Doncaster a few weeks ago and didn't think they were anything special, I took a few notes about them and commented in a previous post about their defensive frailties, I would say you need to be quicker than them today (they are not particularly swift) and you right wing is the place to attack them, they seem quite weak on their left flank so run down that way (is it young Jordan Burns on the right wing?) and you should score a few tries.
Of course, they are dangerous and have their moments but I really couldn't see how they are second in the table, surely an anomaly that, so good luck to the Haven and I hope the match goes ahead.