I had a similar problem re the eating together and eating out.
The short answer is that, yes you can still lose weight if you have the meal replacements during the day and a meal in the evenings, but on the lower calorie Cambridge plans, the aim is to get you into a state called ketosis where you burn fat a lot faster and don't have any hunger pangs. To do this, you need to virtually cut out carbohydrates, so no potatoes, rice, pasta, bread, fruit etc etc.
I compromised by having evening meals that didn't contain carbohydrates - DP could either add some or not as he wanted to his plate. I ate things like stirf frys with lots of chicken and veg, adding bean sprouts instead of noodles. I had big green salads with lots of tuna, made chicken kebabs, stuffed peppers with cottage cheese and put them under the grill ... There are loads of options
The best bit about the diet (aside from rapid weight loss) is the side-effect of not feeling hungry after the first few days, so I'd highly recommend cutting out the carbs as it makes sticking to a diet so much easier if you are not hungry