Short of scaffolding, roof space is best way to go. Walking on the rafters is pretty easy @newbie25 - you could run a decent width plank of timber on too of the rafters so you have something to walk/balance on. Hope that makes sense.
I apologise for the delay in my reply. It's great to see @ProjectPete has already addressed your question.
Since you have potentially saved yourself a great deal of money by finding that you can switch the colouring, perhaps it would be wise to splurge on a handy person's cost to finish the job. If you are not confident in going into the roof space yourself, I encourage you not to risk it and employ some help.