Make sure your double glazed door installer is registered
Building regulations in the UK cover the fitting of replacement windows & doors, this means that once they are installed the double glazing windows have to be certified that they comply with local & national building regulations.
- check out the cost of front doors here https://www.doubleglazing-pro.co.uk/
If your double glazing window or replacement doors installer is not able to ‘self-certify’ that the job is ‘up to code’ then you personally will need to arrange an inspection from the local authority and that will involve spending your own time and extra expense in order to get the appointment to inspect the work and having to pay for the cost of the certification.
Double glazing installers who are members of UK trade associations like CERTASS or FENSA can self-certify and this will save you a lot of hassle
How about a face-lift for the rest of the front of your home? https://www.doubleglazing-pro.co.uk/how-much-do-bow-and-bay-windows-cost/