Recovery partition damaged - how to obtain new Windows media?

Sounds like a bad hard drive is a strong possibility - power on,press F12 at boot into the Dell diagnostics.  Run an extended (2-3 hour) diagnostic on the hard drive -- if you  encounter any drive errors, replace the drive.

It is not necessary to install WIndows 7 -- you can install Windows 10 onto the system from scratch.

If you need the install media for 10,

www.microsoft.com/.../windows10

Thanks for your reply. I'll try the disk diag now. In the meantime I downloaded Win10 from the link you supplied, but when I tried to install it it would not accept my software key (from the Windows sticker on the underside of the laptop). Any idea why?

If you had Windows 7 (non-Pro) are you installing Windows 10 non-pro?

The system should have a digital entitlement - install without the product key and it should auto-activate.

Yes I was trying to install Windows 10 non-pro.

The disk diag failed with an error code of 2000-0145, which indicates a hardware failure. I just spent 45mins on the phone to Dell support. The conclusions were;

- the HDD needs to be replaced

- Dell have received multiple reports of problems running Windows 10 on this machine (slow running, slow booting, crashes and some Windows 10 features not working correctly). They told me that this laptop's hardware is not compatible with Windows 10

They offered to replace the HDD at a cost of £88 (Dell part no 46F6G - a Toshiba 500GB drive), or £110 if the Windows 7 media is included (which I would need of course).

Since this sounds a little steep, I was wondering whether there would be any problem sourcing my own drive from Amazon? Does anyone know of any potential issues using drives not supplied by Dell? The support rep said that they couldn't guiarantee that it would work, but then that's what I would expect them to say. I know that Dell have in the past used "adapted" variants of off-the-shelf components, making it impossible to replace them with independently sourced hardware. Does anyone know if this is the case with their hard drives?

Dell uses standard hard drives - there's nothing proprietary to Dell about them.

You may want to consider a solid state drive if you're replacing - it will markedly improve system performance.

You will likely need a spacer to install a thinner drive.

For example,

www.amazon.com/.../B01BRMEBPO

Thanks - I'll go with something from Amazon. The best deals seem to be on 7mm drives (i.e. Z height), whereas the existing drive is 9.5mm. Should it be straightforward to replace a 9.5mm drive with a 7mm one?

Thanks. Would a piece of cardboard of suitable thickness do just as good a job?

For an SSD, I'd say yes.  If you use such with a hard drive, be sure the fit is snug - you don't want to allow a hard drive space to move around, as shock isn't good for the longevity of the device.