Rainbow, the tin I used was approx 20cm x 30cm. It wasn't difficult to spread the top, it was more difficult to spread the date mixture, although with patience and care it can be done without too much drama. Helps having the base hot. I just dropped large blobs of the date mixture onto the base and then carefully spread it with a knife and found that it gradually softened as it was warmed by the base.
Other comment I forgot to make was that the recipe failed to say how long to soak the dates in the orange juice so I soaked them for about 30 mins.