I did but I had you on the mind having just seen you ?Not sure anyone's mentioned saddle fitter, twice a year minimum, 3 times better.
You need to build up a contingency fund as you will need to pay an excess on any insurance and people tend to forget that - i.e. if you wish to claim for say an accident or whatever there will be an excess. Its a gamble - you can try to keep your premium down but pay a higher excess if you don't think its likely the horse will get injured or you can pay a lesser excess but a higher premium if you think its more likely the horse will get injured. No one has a crystal ball but you can make a reasonable guess.
Also factor in the costs of rugs (two of each weight are recommended for turn out, i.e no fill, 100g, 200g and 350g if clipped) and one of each weight for overnight stable rugging although I make do with layers as its easier. If you have two of each weight for turnout, one can be drying out whilst the other is used.