Re: Mix n Match
Do you usually wear whatever you want and throw on an abaya or just wear long, loose clothing? Because if you just wear an abaya, you can wear the dress alone 
But if you don’t, you can probably wear hte dress over hte jeans and a sweater on top, just like shalwar kameez. Just make sure the dress is not very long. Also, i’m not sure about UK but in US, long shirts/short dresses can still be found in every store and they look great with jeans/slacks.