Joining the dual carriage way as an example - last night I was joining and was around 60mph, upshifted to 5th gear and the revs shot up for a second before the clutch gripped again.
Welcome to Zed ownership
First thing to do is get underneath and check the joint between the gearbox and the engine - you are looking for signs of oil seepage - if the bearing seal has gone it will be running down and out at the bottom, can be hard to tell if the car has any other leaks as it tends to blow back along the bottom of the engine.
While up get a mate to press the clutch you will see the slave cylinder move the clutch "fork" when released the bar inside the rubber boot should be almost loose - you should be able to wiggle it with your fingers if it is still under a lot of pressure then it is not relasing far enough this will contribute to slip. Do the test a few times to be sure it releases every-time.
You don't really need the engine running as there is no assistance to the clutch from the engine - however the load will change slightly with the engine running BUT only try this if safe to do so i.e. you have a ramp don't try it on an axle stand please!!!
If your not sure I would advise getting a pro to have a look for you or maybe the guy that fitted it just to see if he can see anything obviously wrong.
Good Luck
I should have read up more about costs before buying such a nice car - a crappy fiesta would have been a much better option until I have a better job!
I will call my friend and see if I can pop down at some point to get this checked - thanks for the advice but I'm a photographer/IT guy and not very hands on with engines etc.
Thanks anyway
I've read enough of the forums to know we all support zmanalex for clutches but looking on ebay (I know, don't kill me!) there's a LUK clutch and flywheel kit and the seller has really high ratings - is it that risky? Just trying to save myself a few quid