Off your main query, but if you really can't get the hang of a whip finish (there are some good video tuitions online if you Google) you could tie off with two double-hitches, like David Cammiss does:
Thread isn't that expensive, just buy black, white, brown, and olive for starters (or just black in 6/0 and 8/0) to see how you get on. Then buy other colours when you need them. Handy if you have a supplier nearby you can walk into rather than paying P&P every time.
Stick at it, it becomes easier very quickly, and Trout can be very obliging, taking even a beginner's clumsy efforts, which gives you all the incentive you need to keep at it.
Good luck and show us how you get on.
SharkeyP