I wouldn't recommend trying to plan out a build now for Christmas time later. The build components will likely be out of date by Christmas.
If you just want to record at 30 fps, you don't need a £1000 computer. For example, I just built my computer for £360. It will record vanilla Minecraft at 60+ fps and will record graphics-heavy things such as Unbelievable Shaders or Feed the Beast at 30. I'm just on a Radeon 7770, and FX-6300.
However, if you want to be doing some more hardcore things such as video editing/rendering (completely different to a computer than just recording) it may be worth it to spend the extra money and go for the £1000 rig.