I've been to Surrey timbers a few times. I don't think they have a lot of softwood there, but I'm sure they'll tell you if you give them a call.
It's the only timber merchant I've ever been to so I've nothing to compare it too (I want to go to English Woodlands timber in W Sussex, but they're not letting members of the public in at the moment, or at least they weren't when I last checked).
The good things about it are that they have loads of interesting bits of timber (including some amazing tropical hardwoods if you're into that sort of thing) and they're very happy for amateurs like me to go rifling through their stacks. I've only bought oak and some very small pieces of ABW and maple. As said above, I suspect it's expensive but I haven't really shopped around to compare prices.
Matt Estlea did a YouTube video about it which might be worth a watch before you visit.