As Mr Bump says, most of the tax efficiencies will go from first of April so take that into account with the rate you agree, biggest one immediately noticeable is travel expenditure.
Even if you do it for a few months, are you sure?, it could be worthwhile setting up a limited company and depending on your rate expectations register for flat rate vat. Pay yourself the minimum and dissolve the company in a few months for the best tax efficient earning. Although don't take my word for that one, you need to speak to an accountant as I think even that part is changing. I thought it was possible to take the assets at 10% but not sure.
It all depends on your objectives for the next few months. Most of the guys/girls that I work with all go through their an Ltd or offshore arrangement.