I echo what Fleecewife says, especially with this being a small flock that I am guessing you would probably bucket-train?
If your ewes get too fat it can be difficult to get the condition off them and if they are too fat they 'may' not necessarily fall pregnant. If however you can manage their condition none of this should be a problem. (just read khajou's post - looks like this might be a bit of a challenge with Ryelands)
Just a thought, it's a little controversial and may not be a suitable option for Ryelands, but, depending on how well grown the lambs are, another possibility is to put the ram to the lambs and the ewes this year. If you might be interested in going down this route, carefully research the implications such as impact on the growth of the in-lamb ewe lambs, additional feeding requirements and potential mothering-up problems etc.
I also concur with FW and kajou that 'rent-a-ram' might be an easier option for a small flock.