Cleaning House Help

So pretty much every year that I can remember, when I would ask my mum what she wanted for Christmas she would reply "a clean house". I may have succeeded in cleaning the kitchen benches and the dining room table, but have never succeeded in a full clean house (I was still only a child, and lacked the time to do so).

I am now 18 and have realised that if no one else is going to clean the house, then it's going to be up to me to make sure mum gets a clean house this Christmas. I may be able to get her out of the house for a few days in December, but until then I NEED YOUR HELP!!!

Imagine what could be dirty in the house, it isn't the worst case scenario but it it NOT clean. I couldn't tell you the last time the shower was cleaned (I think there's mold growing on the ceiling above it), I don't know when the kitchen was cleaned beyond the benches and stove, we have massive cockroaches living in the cupboards and they are TERRIFYING, out the front of the house all along the front veranda is a redback spider infestation (AND I DONT KNOW HOW TO DEAL WITH IT ???), the guest bedroom is more like a storeroom where you can't see the floor, along with so many other issues I don't know where to start.

I understand mum for not cleaning the house, as she is self-employed and works minimum wage. However, her partner and my little sister also live in the house, and I don't know how to get them to help. Her partner lives in the 'flat' which looks worst than our end of the house, and my little sisters bedroom remains a hygienic hazard and I'm surprised she hasn't broken her neck tripping over yet.

I genuinely have no idea where to start, what to do, what to use, or anything to do. I've got 5 months to get this whole house (interior and exterior) clean and I would appreciate any advice you all could give me.