most conservatory roofs are strong enough to stand on top of - suggest you dont stand on the glass or polycarbonate - but the rafters should be OK. Place a scaffold board or similar across several rafters for additional space to support yourself on.
BE CAREFUL
Some cleaning companies now undertake this work - for instance:
http://www.dk-designs.co.uk/cleaning...tory-roofs.htm
I think you might have a box gutter design? remember they need cleaning out also.
