Hi sedah,
Congratulations on getting accepted for a PhD!
I am sorry to say that self-funding isn't that easy. You might be able get funding from the relevant research council (either AHRC, BBRSC, ESRC, EPRSC) but full funding is unlikely. Depending on your field, you might be able to apply for individual grants from the research council or associated funding body. You can ask your supervisor for some ideas and you can usually find a decent sized list of possible grants with a long google search. However most of the grants are one-offs and probably won't cover all your needs.
Your department might over teaching assistance contracts or marking, which usually pay very well, £15-20 per hour, but they are highly unstable. Again you can ask your supervisor if they can help getting a decent teaching contract. You will probably be eligible for a PhD loan of £26,000 but I know nothing about that. I also know a lot of self funded PhD students that do tutoring, which can be £10-30 per hour.
If I can think of anything else, I will post it here but self-funding can be difficult.