I've found the easiest way to figure out what aircraft you're getting is by checking the WT+ cabin on Expert Flyer. Usually if it is a 772 with 5 rows of WT+ based at LHR then it is likely to have the new IFE and seats. If it is 3-4 rows, then it does not. Ultimately to only way to know for sure is to figure out the registration, which won't be possible until at most 48 hours before the flight, and search the seat map on BAsource.com. For 747s, pretty easy as mentioned above, if WT starts at row 40 then you have the good IFE and refreshed seats. Now, the low-J 747s have been getting some work done on them, so some of them will now have the refreshed seats, others will not, that one is also hard to predict, although there is a thread on here covering the refurbishment where you can use the registration to figure out if it is a full refresh.