Best suck it all in knickers?

[Twork]

I have a lumpy tummy and highs. I have to wear a floaty dress on Saturday so could do with some smoothing. What brands do good smoothing knickers?
I have some vouchers for M&S so there would be ideal.
Also, can you wear a slip over them or do you end up in a bit of a tangle?

I don;t know what works, but the spanx ones are not worth it, especially if you are petite.

(not talking about spanx in general though, they have some good stuff, but the knickers in particular are not useful)

The Next own brand thigh and tummy shaper ones think they are £16 or £20 i wore them for a wedding really comfy true to size. They are soft and are like cycling shorts and the band sits just under bust. I am a 16 and bought 14-16.

I think, since you are wearing a dress, a shapewear slip might be better than pants...slip will smooth everything without bulges over the top.

www.marksandspencer.com/firm-control-sheer-and-opaque-wear-your-own-bra-slip/p/p22232543?extid=ps_gglpla_Lingerie_1343707395_56652787849&s_kwcid=AL!2750!3!262234705368!!!g!729862062632!EFKW&device=c&cvosrc=ppc%20shopping.google.Lingerie%20%3E%20Lingerie%20&%20Underwear%20%3E%20Slips%20%3E%20Wear%20Your%20Own%20Bra%20Slips&cvo_pid=56652787849&gclsrc=aw.ds&&gclid=CjwKCAjw39reBRBJEiwAO1m0OR8R8BCO4lWRiW__h_MmZVJfzl2VR-jxVi9BjGgd9XEdwxU4ji2B5BoCP4QQAvD_BwE&gclsrc=aw.ds&pdpredirect

www.marksandspencer.com/secret-slimming-medium-control-full-slip-a-e/p/p60100009?extid=ps_gglpla_Lingerie_1343203805_56744438307&s_kwcid=AL!2750!3!262235043033!!!g!296929624041!EFKW&device=c&cvosrc=ppc%20shopping.google.Lingerie%20%3E%20Lingerie%20&%20Underwear%20%3E%20Slips%20%3E%20Full%20Slips&cvo_pid=56744438307&gclsrc=aw.ds&&gclid=CjwKCAjw39reBRBJEiwAO1m0OYlEBCt1eknt14HtPcKPG5YiVYfxw-UvgAiIKihCfrduDk1jezMNhhoCBr0QAvD_BwE&gclsrc=aw.ds