How exciting to be considering a dog, and to be at the stage where you can look at a wide range of breeds :)
The Kennel Club have a
breed select tool somewhere on their site which is always worth a play although I don't think it ever came up with what I wanted, or have, or can accommodate - despite trying to manipulate the answers more than once. However it's a fun tool to get you thinking. They also have a lot of other useful advice to help with decision making and finding the right dog.
In order to hep you narrow things down a bit it's worth asking yourself some basic questions - do you work, if so how long would you expect to leave the dog for? I wouldn't have ever considered a dog when I was working but my job was never going to fit into part time hours either, however there are people on this forum that do manage to make it work. How much exercise do you have time for? What sort of walks might they be - in a field off lead or around town on a lead? How much room do you have in your house or garden - does that restrict the size of dog you choose?
Once you've thought about your lifestyle then have a think about the sort of things you might want to do with your dog or wish your dog to fit in with. Do you want to be active and busy or would you like a sofa companion? Would you like a dog that will alert you to someone at your door, or flushing a toilet half a mile away?! Do you want chilled and relaxed, or hyper and energetic? Do you have lots of visitors to your home? Would you like to travel (stay in other peoples homes or hotels and B&B's) with your dog? Would you like to train your dog to do something extra - obedience, general good citizens, gundog, PAT dog etc? Does the dog need to live with or near small furries, rabbits, gerbils or cats for instance? Do you have livestock nearby or a garden full of squirrels?
Finally consider what 'looks' appeal to you. Do you like whiskery hairy faces? Long coat or short? Wiry or soft coat? Would you like your dog to be above or below your knee? Do you prefer ears up or down? Tail up or down?
I'm a wiry whiskery, ears and tail down kind of gal myself and definitely like my dogs above the knee. Funny though how that still fits a wide range of dogs :) My preferences tend to fall into the gundog group first with one or two in the hound group. I find terriers pretty appealing in the looks department but their temperaments don't really fit my circumstances or household. That said I also have a terrier type mongrel who is practically perfect in every way :)
Good luck with your decision making