where can i please find historic UK specific weather information.

I wish to know for example how the weather was on March 18, 1979 in London

Try http://www.wetterzentrale.de/topkarten/fsreaeur.html

and insert the date you want. From my interpretation I'd say it would have
been cold and possibly quite wet and there could have been a little sleet. Not
windy, though.

Tudor Hughes, Warlingham, Surrey.