put the scaff up and get a brickie in. you could prob get one for half a day quite cheap?
did you sort the overheating issue? i'm sure the boiler will keep a while longer 
yeah all I did was put the stat on the boiler back to half and it sorted itself out.
I think you was right about the time it takes to circulate the heated water and the temps it was reaching before lock out on the boiler. No more rumbles or lock outs!
For now it seems alright, but it always is when warm weather comes back
