Leave the study, and leave the bedrooms... if they are your kid's bedroom.. think of changing the duvet covers and curtains. There's always loads of lovely used stuff on Ebay, like last year's next homeware for kids. Kids do not care about aged painted walls.
If money is an issue, leave the extension.. get the space that you do have straight first.
Believe me, kids never notice things like doors replacing. Just sort out the things that really need doing.. and you will get the sense of being in control again.
Ikea have the most brilliant storage ideas... go and have a walk around there, and see what you can sort for your lounge. We use these from Ikea...
www.ikea.com/gb/en/catalog/products/70103085/
And we've put the rattan baskets inside them - and they're rammed with toys. Move alot of the clutter that you feel is taking over your lounge, and put it upstairs in your bedroom or the study. Get underbed storage boxes, again, Ikea do these.
Prioritise the spaces that are more important to you.. and have a good clear out... do you really need all these things?
I've got 3 kids... and never is the entire house sorted! If the downstairs is looking presentable, that's because the upstairs is a poop hole!
I feel like I'm winning if I'm on top of the downstairs living space (lounge and kitchen/diner) and the washing!
Spend some time on your house, and get the storage issue sorted. Them spend a bit of money of getting some nice things, again, Ikea is fab. And get some nice vintage canvases from next, like these...
www.next.co.uk/shop/category-wallart-department-homeware-24?&isort=price&cnt=24
And, you will feel more in love with your house. xx