I bought a big box of glass fuses from Halfrauds, as they only tend to sell them in bulk these days due to low consumption. Didn't cost too much and you end up with plenty of spares (not sure if that's good or bad). I also purchased some glass fuse to regular fuse converters as i got tired of picking out glass pieces
but i don't know of any UK stockists (ordered from U.S didn't cost too much surprisingly). Makes changing out fuses a lot easier as well as finding them. Quite a few ebayers still stock the box of glass fuses, hope that helps!