wrote:

The kit comes in at under £40, most of the cost being for
the harness.

I think you'd be better putting the forty quid towards a higher quality
ladder - I don't think you're going to do much useful for that in terms of
bits of nylon.

What we need then is a controlled decent mechanism, a speed limiter.

If you really want to do it the climber's (safe) way you need something
like this:
http://www.jackson-sports.com/Models...1&ModelID=2486 plus
a proper harness, so a hundred quid.
For a thorough explanation of the dangers of falling even short
distances on a static rope see he
http://www.southeastclimbing.com/faq...all_factor.htm