How to see the best results with weights?

Hi Folks, Just looking for some ideas:

I usually do Body Pump or some free weights at the gym but because I've been training for a run recently my weights have fallen to the side a bit as generally don't have enough time in the evenings to run and do a weight session. I go on holiday in 3 weeks and wanted to make sure I continue to make time for weights but want to make sure what I do is effective. Although I know you cant see miracles in 3 weeks, which im not expecting, I was looking for some ideas/ suggestions on how to effectively burn fat/ incorporate some more weights into my routine to see the best results with the time I have. I understand the effectiveness and results can be determined largely by the food you eat so I do try and eat clean 90% of the time but only human so I do have " bad days" now and again.

Any advice or suggestions on best types of food plans or weight programmes would be welcomed. Thanks in advance