VAT Change for SOLOs

I've been struggling with the VAT change. I've dredged up from my memory the horrors of bills with two VAT rates so I was pleased to find this paragraph in the detailed VAT guide rather than the confusing summary that arrived in the post.

If you are making a single supply of a service which is nevertheless carried out over a period of time which spans the change in rate (e.g. the service provided by a solicitor in preparing a will) the whole supply can be charged at the new 15% rate. Any VAT already accounted for at 17.5% (e.g. on payments on account made before 1 December 2008) may be adjusted using the special change of rate rules described in paragraph 3.1.

I think my IP jobs are analogous to preparing a will so I have stopped fretting as to whether I need to bill all my work in progress before the end of the week. Anyone have thoughts ? The idea of being asked to sub up the 2.5% to the VAT man because I have made a mistake and charged the lower rate when I should have charged the higher one.

So its back to the credit control , oh joy