Dave,
Since no one has yet replied, I'll give it my "stricktly by the book" version. The 01E first grear is intergral to the input shaft, which would necessitate replacing it in it's intirety. The matching gear on the counter shaft would also need to be replaced. I would speculate that this would be a somewhat costly conversion(?). I would think you'd be able to locate a complete O1E with more desireable ratio's, being that you are in the UK.
In case you're feeling very energetic, you might try to chase-down some Euro Audi racing shops or even Audi Sport directly. I recall at one time they were looking to offer a 2.7 first input shaft and gear, which was even cataloged at one time. If perhaps you could locate one of these, then the swap would be very worth while, I would think.
Andy