for a novice rider I would recommend getting an older horse on loan, something that has been there and done that.
Are you a novice owner and rider or just a novice owner? If both then riding lessons before getting any horse I would recommend. And possibly getting a share before taking the plunge of full ownership.
height, breed etc isnt so much of an issue as you are average height and average weight, perhaps a cobby type if you want something safe and steady.
I am starting lessons in the next month, it will be a while yet before I will actualy be able to buy a horse, so should have picked up a bit of experience by then. I had lessons a few years ago but got quite ill and had to give up school for a while so couldn't go riding anymore
probbaly about a 14.2-15hh cobby sort could very easily take your height and weight. would recomend older with some good schooling and manners, knowing his/her job, i would recomend a gelding as they are easier going and better natured in the long terms *says an exnovice with a 5yr old mare* agree with SB lessons all the time, i still have (and need) lessons on my own horse.
I'm 5'7" and weigh the same as you, I'm equally happy on a large pony, lots of the RS cobbies, a 16.3 hunter type and my friend's TBX (who is quite TBish).
Try loads of different types and see which you feel most confident is the best piece of advice I would say - and good luck!
I definately wouldn't dismiss a horse just because it is a mare, and as already stated something a little bit older and a real confidence giver. Loaning is a good idea as you can often outgrow the old school master very quickly and may want something that will do a little bit more. Don't steriotype any horse, cobs are generally saner than TB's but not always the case.. Good luck in your search.. I just adore chestnut mare TB's but not many will advise you to get one of those LOL..
I don;t think you can go wrong with something native. Perhaps a New Forest, which are laid beack, tend to have a good temperament and can turn their hoof to anything. Something of about 13.2hh - 14.2hh will carry you easily and give you confidence. the added bonus for a first pony being that they can live out quite easily. You'll be eligable for plenty of classes at shows, ie showing classes, handy pony, mountain and moorland, SJ, the list goes on..
Get yourself plenty of lessons and do the BHS horseowners certificate. Seek out good livery yards where there'll be someone experienced on hand and have lots of fun planning and saving!
Ditto a native or native cross - nice and hardy. Hafflingers and Highlands are particularly nice. I agree loads of lessons and pehaps a NVQ or horse owners certificate. Another thing to consider would be sharing at a riding school or having a working livery at a riding school. Its a great half way house before taking the plunge completely.