Zorro takes care of daylight saving in the years 2000-2019. You can use the timeOffset function for checking whether the current bar contains 8am GMT.

http://zorro-trader.com/manual/en/month.htm

By the way, your code above is already pretty short, but can be made a little shorter when you substitute

ClosePrice[0] instead of curr
Closeprice[1] instead of prev

You can refer to the elements of a series with [0], [1], [2], .. suffixes.