[kaz]

Try the local Carmarthenshire shows. I'm sure there is someone out there who shows locally to you. Dot might even have a list if you ask her nicely.
If you show him in a Ryeland Class he has to be registered as far as I know.

[Buffy the eggs layer]

You can enter him in a ram lamb class though many of the ram lambs are fed a significant amount of feed so some of them might be a bit bigger than your chap especially if they were born a month or so earlier.
You need to get him used to walking on a halter and to standing before you and being handled if he isnt already. You may want to do a bit of tidying and trimming of his fleece as it grows. If you show him in around the end of July and August then he should be a good size and weight with enough fleece to shampoo and style.
Check out the closing date for entries in the show of your choice and remember to complete your movement paperwork on the day. My suggestion would be to visit an early show in May time if poss and chat to the sheep exhibitors for tips and advice.
Most importantly...relax and have fun!

[Greenmoor]

Beautiful pics!

[Fronhaul]

St Clears YFC is at the Carmarthen showground on 18th May if that helps. 

[Bionic]

Thanks for the info Fronhaul but I think I will need more time than that to get my head round the idea.