FGW drivers (Exeter based) are route learning into Waterloo for when Reading is closed again some time in 2014. I am not sure if it is just between Westbury - Sailsbury and into Waterloo or if it includes Exeter - Yeovil. I would have though that some drivers are maintained route knowledge of Exeter - Castle Cary Via Yeovil Junction & Pen Mill.
There's no evidence that FGW will need to run to Waterloo up the main line again until Easter 2015. (That is, the 2014 Engineering Access Statement has no Waterloo diversions showing for Western Route, although the 2015 version does - for the one long weekend.) As I understand it the Reading station area track layout itself will be mostly finished within a couple of months, and I can't think of anything much remaining to be done concerning the western viaducts that would need the entire route to be closed in the way they did at Christmas/NewYear 2010/11 and Easter last year.
The recent route learning may be more to do with the Whiteball Tunnel blockade, for about three weeks in January/February coming up?