I have a small flock of BWM (and am in South Wales). First year I had two ram lambs left entire, and they went for meat just before tupping time. Next year I castrated, they took longer and didn't finish until Oct-Dec time. This year I've left the early ones entire, and castrated the last couple. Next year I don't think I'll castrate at all. They taste excellent either way.
I've borrowed rams until now, but this year I'm going to buy one in. So it would be nice to think that they can all live happily all year round without any 'incidents', just as darkbrowneggs said. But I also have space to keep the rams separate if need be.
If you are worried about it, maybe castrate just for this first year?
I don't think you can tell a good ram at that early age, so don't register until you are sure he's good (no point wasting money). Look at the BWM society spec list for what you should be looking for, and go to the shows and see what the top stock look like and get chatting to the members.