Ladies and Gents problem finally, unbelievably (to me anyway) solved.
The key here (as many of you pointed out) was leverage. Now I didn't have the right extensions etc for my socket wrench - went and bought an adaptor that I thought would help but it ended up being a waste of $12.50.
Anyway, my crank extractor tool features a 14mm socket with a hex on the outside for a spanner. I had tried this before but to no avail.
1) I left the bolt to soak in WD40 (yes I know, not a reAL penetrating oil but it was to hand) for about 3 or so hours.
2) I tied the pedal to the frame with rope (similar to as reptilezs suggested with the toe straps) so it wouldn't budge.
3) I then put the crank extractor tool over the bolt head, attached a monkey wrench, and used the
now removed fork over the wrench for extreme leverage.
4) It popped right off and came loose easily after that. The cranks and bottom bracket both came out without an issue (probably in part to the 2,000L of WD40 that had sprayed their way!!)
A pic attached showing the leverage chain for punter's reference - no pics of me actually doing it sorry.
Thanks all - all bike problems solved (for the time being). Now to paint strip the frame... wish me luck