1999 td5 discovery es welding

I need to do some welding on the disco. It's an es spec and obviously the battery will be disconnected to do the welding, now I've done some research and not landed at any solid conclusions, so will there be any issues with the battery being disconnected for a good few hours? Or any processes to go few to save any security features on the vehicle before disconnecting the battery?

I don't think there should be any issues with disconnecting the battery for a few hours. When you do, disconnect both terminals from the battery and connect them together with some wire or a big croc clip. This should disperse to the vehicle ground any voltage spikes which might build up, although that might be going a bit over the paranoid top.
Be sure that you know the security code for the radio.

Thanks for the advice I'm not worried about the radio code as it doesn't work and is on my list of things to replace.

I've seen few cases when the BCU failed after welding even with battery disconnected so if you want to be 100% on the safe side better unplug it, it's behind the glovebox

examples: 1. https://www.landyzone.co.uk/land-rover/wont-crank-s-m-d-flashing-and-beeping.261017/#post-3186017 confirmed at post #8
2. https://www.landyzone.co.uk/land-rover/electrical-problems-locked-out.302070/#post-3773581 confirmed at post #9

and i've seen one with my own eyes here as well