Just a quick tip for anyone who has also had blocked windscreen washers:-

Get a can of pressurised WD40 - the one with the Smart Straw attachment. Detach the hoses from the washer heads and pop the heads from the bonnet so you don't get the WD40 all over the paintwork. Insert the Smart Straw into the washer head tube and give it a few good blasts. I recommend doing this outside, as I managed to blow the entire contents of the clogged washer head as welll as the WD40 all over my misses. :-D
This worked so well that my washers will now shoot water to about 15 feet behind my car! Will now have to lower them to point at the windscreen again. Might leave one pointing path side for unsuspecting traffic wardens. :-P

ZZ