I've been through it twice; once in England and once in Scotland. In Scotland it was about 8/9 weeks, although that was delayed due to the limited mortgage valuers in Shetland. The England property was a bit less. In both cases there was no chain

The time could depend upon compllications of land ownership, access rights, mineral rights and so on.

In my experience I heard nothing for weeks and then everything came to a head and a date was agreed quite soon after