To be honest though and I may be "disliked" for this..lol but exercise won't really "tone" up skin
"Toned" muscle is what gives us the lean / nice look. The way healthy muscles sit under the skin but we can't really target actual skin on its own with exercise. Skin can take up to 18months to catch up with fast weight loss but things also depend on your age, how big, how long we have been big for..e.t.c Everyone will be different. Luckily we have to drink a lot of water on a VLCD and thats the kindest thing we can do for our skin for the best chance of things going okay. Body brushing and a good moisturising routine may help to.
Coconut oil is good for keeping the skin supple. Like SR says it's muscle not so much skin and you can't build muscle really on a VLCD. You can probably still lengthen muscle though, so things like pilates and yoga will be good.