In reply to Belayathon: For dedicated rigging use, it is the stuff in your first link that you want.
It is variously sold as abseil rope or static rope but the correct term is semi-static. In all cases it is just rope that meets European Standard EN 1891 and will be 90%+ a single colour, invariably white.
The best place to pick some up cheap (when it is in stock) is often GoOutdoors -
http://www.gooutdoors.co.uk/beal-antipodes-10mm-rope-p143803
The thing you've got to remember is that most climbers who have put the effort into learning to lead climb consider top-roping and abseiling for fun, as activities far beneath their dignity and treat them either as the last refuge of the weak-willed or the work of the Devil. As such, they never really buy rope specifically for top-roping or abseiling. Also, most Outdoor Centres and climbing instructors buy their kit direct from manufacturers. Both of these greatly influence what is stocked by outdoor shops.
What you just need to decide is how often you intend to go top-roping:
- If it is going to be more than a dozen times, you would be much better buying a length of dedicated semi-static (and possibly a rope-protector or two).
- If it is going to be less than 3-4 times you can probably get away without a second rope at all - you just belaying from the top of the crag.
Whatever you do, you really want to avoid using a decent climbing rope to rig with. Rigging ropes are pretty much guaranteed to end up dirty and abraded even if you are careful and protect them as best you can. If you can get hold of an older climbing rope that has been retired from leading with, that is another option that would be ok for occasional use.
HTH
PS You are in a distinct minority as regards using Italian Hitches on scrambles. Along with direct belays they are pretty much the default choice of most of the professional Instructors and Guides I've worked with.
PPS I've got around 25 metres of 11mm Mammut semi-static sitting here that has been used perhaps twice that you would be welcome to for £25 posted.