I bought a couple of David Austin roses from the local GC earlier this year.
When I planted them, the root systems were minimal.
If they do try and flower this year, should I cut the flowers off to promote root growth ?
it wouldn't make a lot of difference to them, as long as you plantede them correctly, and applied some BFB or similar to the planting hole, you should have no problems! ;)
Most of the roses I've put in have flowered the first year, and it's never held them back at all.