hates pulling away

Ah sorry, idle control valve, no, has no effect when you are pushing the pedal. Causes ridiculously fast idle or stalling at tickover when gone.

The catalyst blocks up inside. You can take it off and whack a hole through with a broom handle, but it will not pass the MOT next time. Also you might get the engine management light to come on if there are 2 exhaust sensors, one each side of the catalyst.

What was the last thing you did before this happened? It hasn't grown bigger tyres or something has it?

i havent done any thing it is standard its been doing it
for a while funny you should say about high tickover when it
rains for the first 5-10minits it reves at about 2500 rpm with
no load on the engine which is quite high when i pull up at
a junction and dip the clutch

when its not been raining it is very easy to stall if you were
doing a hill start you would have to rev the engine and slip
the clutch more than you would on a normal vehical
its almost like you dip the clutch put it in gear and as soon as you bring the clutch up just befor its got any load on it the reves drop and it stalls i think i am now in the habit of
bliping the throtle as i pull away i think other road user must
think im a boyracer or impaitent

Meaning, the baffles and chambers inside the catalytic converter have deteriorated and plugged exhaust. Not visible, unless you see actually have holes on the outside, but you would notice the exhaust and noise. It's over ten years old, cut it out and straight pipe it for now.