Replacement for felt pipe insulation in roof space?

[nusku]

I want to replace the insulation on the pipes in my roof space. Im going to use Climaflex but I'm unsure of what wall thickness is required. All the runs are about 4m long except the mains water which is about 6m.

1. 22mm hot water cylinder vent
2. 22mm cold water feed to house
3. 22mm cold water feed to cylinder
4. 15mm cold water feed to power shower
5. 15mm mains water
6. 22mm heating vent
7. 15mm heating feed

I have a stash of 15mm with a 25mm wall and 22mm with a 19mm wall is that suitable for use on all the above pipes or do any of them need thicker?

Should the pipes be insulated in the airing cupboard and in the floor void?