If anyone is deperate to bake, the book has a few recipes with almond flour instead of wheat. They sound tasty 
800 cals daily will lose weight for almost anyone, but you'll see greater loss and almost certainly more improvement in insulin metabolism, if you cut out the starches so you are actually doing the BSD.
Also, starches make you hungrier later, so less likely to keep to 800.
If it is too tough, ease more into the 5:2 BSF, by adding one or more days nearer TDEE, but still the same foods, i.e. no starches.
A piece of cheddar cheese, or a tub of cottage cheese, with a handful of almonds is a v quick meal.
Obs If you all eat the protein & veg, but the teens have bigger portions plus lots of starches (like chips !) it works easily enough.
e.g. for sunday roast, you eat lean meat & masses of different veg, horseradish sauce; the rest of the family add roast potatoes, yorkshire puds, gravy.
Millie I posted upthread that anyone taking meds - e.g. insulin, bp meds - needs to work with their doctor in case they need to reduce the dosage.
Some people foind after the BSD they had reversed T2 and lowered bp, hence no need for any meds. Some needed much lower dosages.