OP I do matched betting plus casino offers. I would go back to sign up offers and reloads until you have made that money back.
What % of your bank was the £200? Because if it is more than about 20% you really can't afford to do casino yet, the variance is too high.
I make probably 90% of my income from casino, but can afford to ride out the variance. I also hate casino, I don't get a buzz from a big win, I don't chase. I do mainly high risk stuff and have days where I can be a couple of hundred down. The only thing that upsets me about being down is the wasted time, not the money.
You have to have the right mentality for casino. And the bank. And the knowledge. And most importantly the discipline.
Unless you have those then dont do it. And if you do it, have your exit plan and maximum deposit before you sit down. Write it down and keep looking at it.
I have known people blow their entire bank, £1000's rather than £100s, chasing casino or just pure gambling. I'd withdraw every penny and spend it before I did that.