My advice as a follows:
- Find out which UK courses transfer to any of your target schools.
- Figure out which courses (GE’s and major prep) you are required to take for transfer and take them at a community college
- Do well at said community college and it might help mitigate the lower grades received at the UK school.
- Figure out how much you can spend to complete your CS degree. I agree at minimum at least 3 years.
Best of luck.