OU is fine on reputation imo. I would say its more about Uni experience. Think you are going to have to do the spadework and contact Unis direct as to whether they will take you. the higher up the food chain you o the more difficult it will be,. Law is quite good because it is modularised, but they can be fussy as well. Make informal contact and then follow up with a more detailed enquiry and you will probably need your transcript.
Make sure you are clear in whether you want first or second year entry. Make sue the place you are going to is better.