Tvheadend

Sure. Click and select the first one. Then Shift+Click on the one at the bottom of the list. Now all of the channels are selected. When you click the edit button, your changes will apply to all selected items. If there are some you don't want selected, Ctrl+Click on them to invert the selection of that item.

Ah, this is great, thank you! I tried this before but this time noticed the tick boxes on the left hand side that I have to tick for it to work!

Thanks again!

Looking at your screenshot, perhaps what you are looking for is "map channels, merge same names". That will get rid of lots of your duplicates by merging your nine Channel 4s and numerous Channel4+1s. This will then leave you with fewer channels you need to manually disable.

Perhaps also take a look at the bouquet tab. I don't use it, but I know people tick the one box for their region and have it automatically map only the channels from that region so you only get Yorkshire or London channels, avoiding the other regions channels.

You probably need to delete your existing channels first before doing either of the above.