hi, i have completed B.E.Mechanical engineering last year and i do have standing backlogs. i want to do M.S. part time weekend class in uk

Normally international students are not eligible for part time courses. You can get visa only if you go for full time courses. without completing the degree you will not be accepted for masters. You may be able to get final year of the degre baseed on the papers you have cleard.

You need to complete all the requirement of your B. E before you can enroll for M. S.