Is there a way to keep the original UK layout of the keyboard whilst still typing in Japanese? I hate not being able to find symbols I previously knew the place of, and have to keep switching back to English. i.e. I want the ? (pound) symbol to be in the same place all the time.

Just setup a hotkey to change between keyboard layouts. I would tell you how but I abandoned Windows (which I assume you are using...) a few years ago.

[ファブリス]

If you mean the english key layout while in IME mode, there's no easy solution, but someone posted here a link to a Windows Software to remap keys in the IME. Can't remember what the topic was though..

Yes remapping the keys seems to be exactly what need to do...the lord google may have the answer...