If it's any help, it's worth it when you get to,the end. Similar issues, house owned by two previous bodgers. Dodgy wiring, damp, no insulation, knackered and inefficient central heating... In a 4000 square foot property in which very room needed rewiring, replastering, re carpeting and redecorating.
The inside is nearly complete although there are still big big jobs in store... Our living room floor, in beautiful solid oak, was installed over a pile of rubble with no damp course, meaning at some stage in the next few years, the lot is going to rot through and collapse, meaning we are going to rot through and I'm going to have to rip up the lot, and put in a block and beam floor.
The garden in parts is currently a memorial to the Somme.
I still need to put active ventilation in though the house as the attic cold space is damp.
Think of it as a marathon and not as a race! Always try and keep one part of the house clean though as you will be miserable if every room you go into is filthy. We were lucky we have an annexe meaning we could decamp there when things got bad in the house.