I want to put some longer cranks on my coker but do not want to put ventures on (i want some Q on my cranks…).
PM sent. Let me know if it can helps 
Since you’re in the UK, I would say that these would be hard to beat:
http://www.unicycle.uk.com/unicycle-parts/cranks/steel-standard-cotterless-cranks-chrome-152mm.html
8 pounds the pair – what a bargain!