Hey Emma! Congratulations to you and getting healthy and fit!!! I am a certified exercise physiologist in Canada. I don't practice any personal training anymore, however, I can hopefully answer some of your questions.
First off, don't eat all no fat or low fat foods! Fat is important for our bodies and the stuff they put in no fat/low fat products is worse for you then eating good fats. They add products that our bodies can't process and isn't sure what to do with it and so the body just ends up storing it as fat! With that said eating good/healthy fats are important (just not eating too much of it is key). Things like salmon and avocado and olive oil and nuts are filled with good fats that will fill you up and energize you. I am not a nutritionist, nor do I want to sound like one but just make sure to eat healthy, whole, clean foods, and you should be good!
Secondly, I would HIGHLY recommend a website called www.sparkpeople.com . Its an amazing website where you can input your information (height, weight, etc) and put in your goal and it will tell you how many calories, protein, fat, fiber, etc that you should be eating everyday and then you can track all of your food in the tracker. Then it will also tell you how many calroies you should be burning on a weekly basis in accordance with your food intake. Making sure you are getting the right amount of calories, fat, and protein are very important if you want to lose weight. Nutrition is 80% of the job. Exercise is 20%, Don't get me wrong I think exercise is very important in an overall healthy lifestyle but its A LOT easier to refrain from eating 250 calories (one chocolate bar) then burning 250 calories (1 hour walking, 30 min running).
They have A TON of exercise videos that you can use at home if that's the most convenient for you! They always have 30 day jumpstart bootcamps which you can follow that start out with only 10 minute workouts. I would recommend investing in some hand weights, start out with low weights and as you get fitter you can purchase heavier ones.
As for personal training; there are some trainer who will do in-home training or you may have to join a gym. You'd just have to check around your area where you live. Either option is going to be pricier then Sparkpeople (which is free!); however, I would recommend a trainer if you want someone to be accountable to. There are many different types of packages, some people will go once a week and do the remaining workouts on their own and just use them to check in, other will see trainers 3 x a week. Its really up to you how often you want to see them.
A trainer should never shame you or make you feel embarrassed. They will probably push you to do things you've never done before but you should never feel ashamed or embarrassed.
Is it going to hurt.... well if you've never exercised before and you start weight training... your muscles will probably be sore, but you will eventually become less sore.
Hopefully this helps you a bit!