mumtomoley Due to the timing of your various meetings - ie staff appraisal after pay rise meeting - I would request a separate meeting with your boss before pay is reviewed.
(In our organisation the financial year is October to September and pay is reviewed around now so if it is the same where you work, I would request the meeting asap.)
Otherwise, if you wait till your appraisal, your boss can get away with saying "Sorry, we've just reviewed salaries, you'll have to wait till next year".
As for what to discuss in the meeting itself:
I really need the extra money
I'm sure you wouldn't mention that in the meeting but keep that out of any discussion.
I know roughly what the rest of the team are on and I think I am paid comparitively lowly
I also wouldn't bring that up or that you will start looking for a new job if they don't give you a pay rise.
Instead, stick to the facts and give some good examples and facts based on this:
What I know now, and therefore bring to the team compared to four years ago I think deserves a payrise
Finally, if he says that he can only give you the inflation rise after your meeting, I would then ask "What would I have to do in order to significantly increase my role and pay within this organisation". It may be that, sadly, there's no chance of things changing whilst this boss is there. But at least you will know and be able to make your plans accordingly.