.......An update......
Thanks for the post Mysterons (and everyone else's encouragement), it was the nudge I needed and with that allowed me to align my rows/columns.
Current progress is, solved and entered into grid:
2ac,3ac,4.1ac,8ac,10ac,11ac
1d,4d,5d,6d,10.2d,12,1d
Solved but not entered:
1ac(due to uncertainty over 1.2 answer),5.2ac,6.1ac
Feels better having the grid partially completed, and am confident of all the answers i've entered into the grid and their position......now just have to see if I can work out the symmetry of clashes etc and get some more clues in!!
Philoctetes is correct it is fascinating how differently individuals fair, i'm clearly lagging here, but appreciate everyone's support and the lack of arrogance from all the succesful solvers, many thanks!
Keep at it Deviant, and Chambersreference.com has a handy 30 day trial if you don't have the sacred Big Red Book to hand.