To reiterate what has been said already but applying to all of Durham
1) You can't swap colleges at this stage, unless you have an incredibly good reason (medical etc.) that means your college does not fulfil your needs.
2) Within most colleges there are a number of shared rooms. You don't find out about/ apply for rooms until you have finally accepted your offer after results day in August.
3) That being the case, if you wont ever consider sharing a room you shouldn't pick Durham. However, in my opinion this is being remarkably short sighted. Durham is an amazing university, with fantastic prospects, and the college experience is pretty unique as a whole.
4) They really do put a lot of care into matching people up. Many of my friends found their room mates were one of their closest friends for their entire time at Durham. The questionnaires are very detailed, and whilst it is done by people they are generally very good. You compare it with OKCupid - that's quite different as they are matching people up for relationships. A relationship and whether or not that works out is very different to whether or not you are able to live with someone for a year! Many people say sharing a room actually made their experience better. Shared rooms also tend to be very big.
5) In some colleges, people swap rooms in different terms (not sure if this applies to Hatfield).
6) Most colleges enable you to say which kind of room you'd prefer, and they do take this into account. However lots of people say they want single rooms, and they have to give priority to those with valid medical/ other really good reasons (backed up with evidence, eg. doctor's note).
In your case, you really don't have any option other than is it worth giving up Durham entirely on the chance you end up having to share a room for a maximum of one year of your life, where you'll probably be sharing with someone fairly similar to you/ you will quite likely be friends with?