Thanks guys for the replys.
UK clocks I believe wont work in that the plugs are different to the later cars, so I needed the later type as I want the cluster to actually work incase they notice that nothing is working, then it would be a whole repeat session.
The ebay dial I posted about will work ok I believe, but as mentioned it would be nice to have 180mph when going to the hassle of getting a cluster, buying a new fascia and then having to remove the needle and install etc. Plus I may have another series 4 TT manual coming and its also in KMH so this new cluster will suit that also.