It's the sort of thing I'd be reasonably happy to do myself but wouldn't endorse anyone else doing, if you know what I mean.
One thing to remember about fuses is they're not very good or very quick at dealing with small overloads, so if you accidentally turn on too many rings you can draw quite a bit more than 13A without the fuse blowing. IIRC the standard British fuse spec allows something like 20A to be drawn indefinitely.
In theory things protected by 13A fuses have this design margin built into their own spec so they won't melt or catch fire before the fuse blows. But it's not something you want to be relying on.