Another hours question (yes im confusing myself)

in thinking of changing my shift pattern so that i have everyother friday off rather than every other sunday as i can see im going to have dentist optition and builder apts coming out my ears soon.
assuming i work 8 hour shifts 14.30-22.30

last week i worked monday tues wed off thurs and fri then worked sat sun (so full weekly rest ie thurs and fri)
this week i am working mon tues wed thurs off fri and sat then work sun (full weekly rest as off fri and sat)
next week im down to work mon tues wed thurs and fri off sat work sun (reduced rest??)
week after i would like to mon to fri off sat work sun - thurs but i dont think i can is this correct?

Im annoying myself with the repeated circular postings has anyone done a spreadsheet or is there an app that allows you to enter the days you wish to work?

No you cannot legally do what you want because you will have only reduced weekly rest periods of 40 hours in both weeks 3 and 4.