Welcome @ti3unutac!
Lots of tips in the forum and this website - probably best to read thru the LEARN pages on topics of interest to you.
Try to avoid snacks on fast days - drink water, black teas and coffee, salty drinks (stock cube, miso soup), and keep as busy as possible to avoid thinking of food. But if you have to eat, then options include a boiled egg, a few Brazil nuts, some berries and no-fat good quality yoghurt, a small piece of hard cheese. Keep the cals as low as possible. I am sure others have other ideas too.
If you find 4:3 too hard, I would suggest 5:2 as perhaps an easier way to start. On the whole, I think people have lost weight at the same rate whether they followed 5:2 or 4:3. It's more a case that some people find the discipline of almost every other day fasting easier than just twice a week. But it is whatever works for you.
Going to the gym sounds good, providing the program is tailored for you. Depending how vigorous it is, it can work well for a fast day activity too - something else to occupy you! But just increasing the amount you walk every day - use a pedometer - may be a gentler start to exercise.
Good luck and best wishes.