Will it be OK ? Yes
Will it be Great ? No
I'd ditch the dextrose altogether, swap the 500g dry malt for some liquid malt from a coopers tin (Light would suit the brew) and go from there. Won't pack as much punch but will taste a bit better. Maybe some Saaz hops in there as well and ideally you'd use W34/70 (or whatever it is) and brew at less thn 15degs.
Otherwise, what ya got will give you beer, which is the aim at the end of the day :chug: