52k seems really low for the gearbox to be "worn" out.. especially on a low powered version, I guess it depends how it's been driven - my GTI with 300lb/ft and 150k on it had a new clutch/dmf recently and the gearbox was good.
You can get the gearbox rebuilt, but it's not cheap... £1200 for a "new" gearbox and clutch fitted isn't too bad a price really.
There's also the option of a reconditoned box, which they then take your box in Part Exchange, should work out cheaper... I'm assuming the 1.6 doesn't have a DMF so that cuts the cost quite a bit.
Labour isn't massive on these, don't pay more than £250 for that, personally I wouldn't use a new box on such an old car.