CX seems a good choice.
If you aren't sure, and don't want to chuck money at it , in case you don't like it, the Voodoo CX from Halfords would use about half your £1k budget.
I've had one for 18 months. Done thousands of miles on it and can't complain about the bike at all.
In hindsight , now I'm used to that style of bike I sometimes think I should have maybe spent a bit more, but what if I hadn't liked it.
Good luck
If you aren't sure, and don't want to chuck money at it , in case you don't like it, the Voodoo CX from Halfords would use about half your £1k budget.
I've had one for 18 months. Done thousands of miles on it and can't complain about the bike at all.
In hindsight , now I'm used to that style of bike I sometimes think I should have maybe spent a bit more, but what if I hadn't liked it.
Good luck