Hi, just an update on this.
The suggested links above wouldn't work for me but you may have better luck but thanks for the effort to help.
I returned to the UK and had a browse on eBay for replacement lens or back cover. Not sure that I can add the link here but if you search for "Nokia G42 5g back frame" you should find what I bought.
The back frame comes complete with screwdrivers, spudger and some thin strips of doublesided tape. Everything that you will need to make the repair.
The lens cover can be removed from the frame by heating the lens area (I set the frame on the radiator while I removed the back cover from my phone)
Using the blue levering tools that come in the kit, I pryed the lens section from the new back frame.
The lens "glass" is actually separate and can be popped out using some heat but I elected to replace them as it seemed easier.
After removing the original adhesive from the back frame, I applied the supplied tape around the lens frame and mounted it and it seems secure enough.
The lens glass then needs to be installed. These are small, fiddly to handle and they are sided ie, there is a side with the black border printed on it, these are applied with the printed face inwards.
One minor problem is that all 3 lens glasses have the same size border unlike the original ones which have a thinner border for the main camera. I don't have a side by side comparison but I suspect that it will narrow the field of view for the main camera.
I contacted the seller on eBay but they have not responded...
So it's a fix of sorts. I now have a camera with no glare as with the cracked lens. Field of view, hard to tell but I mostly use a partial panoramic mode for pics to get a bit more in.
Worth a try if you need to replace your camera lens.
The job itself was easy enough having never done it before.
Hope this helps anyone with the same issue.