I'd look at getting closer to 52 minutes if I were you. I rode the Shaftesbury middle marker event last year in similar conditions to Saturday, got to the turn in 35 mins, back in 25 for a 1:00:19. A couple of months later I managed a 56:36 on a half decent day.
I think a 52 would be possible, but only on a very good day. Still, it's something to aim for. The club record was lowered this year on the E2/25 to 52:09, which isn't entirely beyond reach...
I'd look at getting closer to 52 minutes if I were you. I rode the Shaftesbury middle marker event last year in similar conditions to Saturday, got to the turn in 35 mins, back in 25 for a 1:00:19. A couple of months later I managed a 56:36 on a half decent day.