Need help please !

Losing fat generally requires an energy (calorie) deficit (using more calories than you're taking in). Gaining muscle generally requires an energy surplus (taking in more calories than you're using.

Doing both at the same time can only be done under very limited circumstances, such as an obese person whose vast fat stores can support the increased energy deficit required to build muscle while depleting fat stores, or someone eating essentially at maintenance or very close to maintenance (in either direction), so that, again, their fat stores can keep up with the added energy requirements of building muscle while depleting fat stores.

Essentially, it's next to impossible to see significant fat loss and significant muscle gains at the same time if you're not starting out obese, which you're not. You need to decide which goal, at the moment, is more important to you -- lowering your weight to 11 st or gaining muscle. You can always switch to the other goal when you reach the first, or even switch mid-stream if you decide that's advisable.

In any case, losing weight while preserving muscle (or possibly gaining very small amounts of muscle) depends on keeping your energy deficit small (I would advise 250 kcal daily deficit), getting plenty of protein, and challenging your muscles with progressive resistance.

Gaining muscle while limiting fat gains similarly depends on keeping your energy surplus small (because what your body doesn't use to build muscle it will store as fat -- again, I would advise 250 kcal daily surplus), getting plenty of protein, and challenging your muscles with progressive resistance.

Of course, if you've got a time deadline for weigh-in for the beginning of the season of whatever sport you're talking about, those small deficits may not work for you, in which case you'll just have to load up on protein, lift wisely (don't forget rest days, because you build muscle on rest days, not on training days), and hope for the best.