Firstly, congratulations on your house. You may not like it now but surely it screams potential at you and you can make it a home.
Secondly, no one is born with a paint brush in their hand and the ability to cut in an incredibly neat line. It is a learned skill and like with anything DIY it will save you hundreds if not thousands in labour if you learn to do things yourself.
Youtube is an incredible resource for learning how to do things. As you are looking at decoration at this stage then I can recommend Charlotte a professional decorator on Insta who shows you how to do things. I am now 50 and have been decorating since I was 15 years old. Dh and I have decorated, plumbed in bathrooms, tiled, installed flooring, put up walls, gutted gardens and I draw the line at plastering because I have a plasterer who is pristine at the end of the day, ie no splats on him or my floor or ceiling and the walls are like glass. Costs roughly £250 a day for a sparky or plasterer plus materials. We are in Yorkshire.
https://www.instagram.com/charlottedecorator/
The best advice I can give you is start small and I don't mean one room I mean one section of skirting board. Choose skirting that will be hidden behind furniture and start there. Use water based paint and it will dry fast allowing you to get 2 coats on easily. I have literally done one wall at a time in my bedroom due to how much furniture I have to move, so pull bed and bedside cabinets off the wall, paint, second coat, when dry push everything back. Then tackle the next wall when I have time.
Personally I would allocate maybe one Saturday a month to tackling stuff like DIY. Regrouting is easy if you know how to do it, I removed the mortar from my patio, you need the right equipment and tools and as I said Youtube is incredible for this, watching people renovate houses or professionals who share their knowledge.
The mould remover @Svalberg recommended is the absolute best thing out there. You can always post on here and ask for advice on what product works best for whatever job you are doing. I honestly wished I lived closer to you, I think skill sharing is something we have lost with people moving all over and away from family who are possibly able to teach stuff.