Just checked UKForex which i have used once before, they give you 2 free transactions then after that 50 dirhams for transactions less than 30,000 dirhams otherwise free.
At today's rate 100,000 dirhams buys £16,677, rate 0.16677
Emirates NBD charge 50 dirhams for a local transfer to UKForex Dubai account, it took about 2 days to reach my UK account