Owning your own home

Small bathroom only out of that lot I would say.

In terms of adding value when selling:

1. Roof insulation in the loft rooms (they're freezing in winter, stifling in summer)
   Not worth it
   
2. Radiators in the loft rooms (inefficient without the above, but might make it more bearable for a lower price
   Not worth it
   
3. A decent sized family bathroom in place of one of the bedrooms
   Maybe worth it, depending on whats sold in the area, and what it'd cost all in with re-plumbing, maintaining water pressure etc
   
4. A renovated small bathroom in the place of the current ugly tatty small bathroom
   Will probably add value if you can keep costs sensible
   
5. Stairs that no longer creak
   Can this be done by nailing existing planks? or will it require something more drastic?
   
6. New windows (it's a corner house with two sets of double bays)
   If they are nice original bays, just paint them and make the existing look nice
   
   

Id caveat all the above- it depends what the market is like when you come to sell, and what buyers in the area are looking for . Looking at recent sold prices and listings online will give you an idea of what local buyers are after, and what improvements have realised higher sale prices on recent sales

None of them if looking at pure roi - better off sticking the cash elsewhere I’d wager

But which of those would improve you life for the next 1,2,3 years ?

Lick of paint for the small bathroom.
Stairs if you can easily / cheaply.

If it's a bit tatty in places repaint front door/hallway for first impressions but none of the others are worth it IMO.

I’d just try to ‘equalise’ the house so there’s nothing glaringly out of whack. That might be doing the small bathroom and putting rads in upstairs - if they are actually missing.