What to do first?!

[chickeninabun]

I'm just waiting for a cheque to come in then I'm wanting to book my pony in for a back check (nothing serious but she does have a swayback), saddler and (possible) new saddle fitting and some lessons.
But which should I do first and in which order?
I'm not entirely sure I need a new saddle and it seems to fit ok but slips when schooling (i.e. cornering on the cob x steam train x motorbike) so not sure if it's the saddle or my bad riding, so obviously need some lessons. And again I don't think there is anything wrong with her back but as she is quite dipped it seems the sensible thing to do.
Any thoughts?
x

 

[Nailed]

back then saddle then lessons.

Lou x

 

[happihorse]

Back first, then saddle check and the lessons!

 

[chickeninabun]

And another question..
On the back person's website it says she needs your vets permission to look at the horse. My vet hasn't seen my horse yet (I haven't had her very long) so should I just phone them up and say "I have a new horse and want to get it's back checked, is that OK with you Mr Vet?" Then just tell the back person that the vet was ok with it, or do I need something in writing?