This is a nice idea molly, but it's such a matter of personal taste. If I were you I would spend some time looking on-line or in catalogues - even Argos can give you some choices for starters - there are so many designs and weights. You could have a bangle watch, or one with a strap, or one with a pattern link chain - round face, over face - white face, - delicate, more chunky - the permutations are endless!
Most watches these days are quartz - battery-operated so you don't have to worry about winders breaking - there are many reputable brands and you should find that all of them come with a guarantee of some sorts. The cheaper watches are sometimes less reliable than well-known brands.
So glad you have made a choice, if you have tiny wrists like me (only 5 and a half inches) a neat art deco design is classsic and will last you well. Have a lovely birthday. ♥