As I understand, the problem is the corrosion between mixed metals and not the loctite.
Well Huzzah! (in relieved tones...)After various failed attempts to remove the stuck bolt, I finally resorted to cutting the disc and managed to get it free. Underneath I found the sort of corrosion you usually get on electrical parts, so, for the hell of it, I used some WD40 Contact Cleaner on it and then grabbed what was left of the bolt with a pair of mole grips...... and the bloody thing moved!!!So very carefully, with lots more cleaner and regular WD40 I slowly unwound it and it finally came out.Now I just need to wait for the new bolts to arrive on Tuesday and I'll be sorted.Thanks to everyone who offered help and advice.
Glad you’re all sorted. Hope the surfs up for you next weekend.