Thanks for all your replies! I've ended up buying some 2ft battens from Screwfix. I have a double garage, and thought I would need 6 3ft ones, but couldn't find any/many that length so I started with a pair of 2 foot ones to see how bright they were...and also kept my original 3ft led tube. Certainly makes a difference - enough light for pretty much all of the garage, but the two new ones are mounted on one side, so I either move them to the middle or get a couple more to balance it out.