You register with the bonus code and deposit £10. You then get two bonuses added, one for £10 which is the standard 100% bonus, plus another £25 which is the weekly bonuses bonus.
The £10 bonus has a 4x wagering requirement. The £25 bonus has no wagering, but you need to bet it through to get it out of your bonus balance. So in reality there is a total combined wagering requirement of £65.
If that is too high for you, then you can decline the £10 and just play with the £25 bonus.
Hope that clears things up!