A wagering requirement of £350 doesn't sound like much but with a starting balance of just £10 you have to be incredibly lucky very quickly in order to stand much of a chance. Playing slots in this situation is basically suicidal so I'd recommend going for the video poker games despite the awful contribution percentage of just 5% at this casino. Bank all of your small wins and just keep playing in the hope of hitting a couple of double ups whenever you win a straight, flush, full house or above. This strategy usually helps me to get up to around £25-£30 or so at which point I'll try blackjack until I have a balance of £50 or more and finally hit the slots to actually start knocking that wagering requirement down! If you end up back at £10 go back to the beginning and repeat the process... if your luckier than me you might just manage to clear the requirement, but it's still difficult to find yourself with a balance worth withdrawing!
It would be nice for a token gesture such as this to be awarded without any pesky wagering requirements of course, and some casinos do actually do this... but I can't blame Casilando for choosing to make this a regular bonus deal. It's not the most generous offer around but considering it's so easy to get and can be claimed unlimited times it's a nice option to have available.