If you download the .csv version of the data which DC10Fan links to on the CAA website, ie from here:
http://www.caa.co.uk/docs/80/airport...e_Analysis.csv
and put it in Excel then you've got a way of trying to calculate load factor. Then you'll need to work out the capacity on the route - check out WW and FR's number of flights (both ways since the traffic is for both directions) by aircraft type and capacity and sum them to give a total for the month. You won't be able to work out the load factor for each airline as the traffic isn't split, but you will see the overall route load factor for the route.
As I said earlier, the airlines, airport and CAA will have the breakdown by carrier, but it's not available to the general public.