In reply to siobhan66:
Hi. I had the toes adjacent to each big toe fused when I was in my mid-late teens. I was offered a Jones tendon transfer, but opted against it out of fear. As to how the fusions will affect you, I think that really depends on what/how you climb...
I've never been one for wearing tight rock shoes - I like to be comfy! Consequently, not being able to crush my toes into horribly downturned things hasn't proved a problem for my sort of grades (E2). It hasn't made a scrap of difference in big boots, so no issues there. The scar tissue can be a bit annoying in some shoes (post-op infection resulted in lumpiness). The only occasions on which I've found it to be at all annoying are when trying to find a tighter sport/wall climbing shoe: because the toes won't bend, the front of the boot has to be pretty low volume.
Ultimately though, it certainly won't stop you doing things. It might change things a bit, but its something that is completely adaptable to. Personally, I think you may well find the scarring the biggest problem, especially for long, hot days. But that's easy to get around with a bit of careful foot prep. Boots used to sell, and I think they still do, finger/toe-sized jelly-like socks wrapped in plaster-like material. These are great and can be cut to an appropriate length.