Switching from Slimming World to MFP

Squatsandbench

Hello,
So I am getting married in just under a year and I am looking at dropping from 12 stone to 9 stone 7llb or there abouts.
I joined SW two weeks ago (on again off again) and I really cannot do it. So I am looking at doing MFP. I calculated my TDEE - 20% which gave me a calorie count of 1670. So I am going to follow that with swimming 2-3x per week. I will also try to increase my movement generally with a fitbit or something similar.

I will be looking at getting my wedding dress in June this year so I guess i have about 4 months so much pressure it is quite stressful but even at 1lb a week that will get me to 17lb down which is needed!