Replacing double glazing. Suitable DIY job?

Hi everyone

I am in the process of buying a new house and in the whirlwind of exciting decisions to come I am thinking about the windows. They are all old and need replacing. I had a few windows and front door put in my old house and the company offered a measure and supply only option. They fitted the windows last time. But this time I am considering doing it myself to save money.
I consider myself fairly competent and always do lots of research for my DIY. I've fitting my own bathroom and done a couple of kitchen to a really nice finish.

Is fitting double glazing myself going to be a possibility? Or is it one of them jobs that might look simple enough but is actually a nightmare and best left to the professionals? There are no bay windows.

I am aware I'll have to get BC inspections etc.

Thanks

If you've done kitchens and bathrooms to a good standard, basic flat casement windows are totally doable. The physical fitting isn't rocket science, but the devil is in the details.

A few things that usually trip people up on full-house DIY installs:

Measuring clearances: Don't measure tight. Take the smallest opening size (width and height in 3 places) and subtract 10–15mm overall for expansion, shims, and foam.

Toe-and-heeling: If you have opening sashes, look up how to properly pack/toe-and-heel the glass units. If you just drop the glass in square without bracing corner-to-corner, the sashes will sag and rub within 6 months.

Building Control fee: Check your local council’s Building Notice fee first. In some areas, the BC inspection fee for DIY replacement is so steep that it eats up half the savings compared to using a FENSA/Certass registered fitter.

Ground floor windows are easy enough to start with. If you do go ahead, buy a proper glass lifting suction cup and a good non-metallic glazing paddle — they save a lot of grazed knuckles.