Just to update, I got the Fiat back.
Gearbox was sent away to be re-conditioned (£335 + VAT). New clutch fitted. The garage fashioned their own gearbox mounts. There were various components changed, seals, linkages etc. and a lot of labour to get the gearbox/engine out due to seized bolts.
All sorted now but at a cost! There were other bits too, but gearbox/clutch problem amounted to about £1000 with VAT.
Hopefully car will be good for years to come, or at least the gearbox! The gear change is totally different now, so much more slick, and the drive much quieter.
Best wishes
Chris