First thing download my fitness pal and track what you eat, so this for a week, carry on as normal.
Then start cutting back tiny things. So take out sugar in coffee, then reduce to 2-3 coffees, then drink with out milk etc, just gradually.
You'll gradually get use to that.
Then start each meal with a protein source, and build around that, use food you actually like, no pint eating kale if you hate it!
Then start to reduce portion sizes, week by week so you gradually get use to it, keep eating your normal food, to gradually ease into reducing the amounts.
Then exercise, a walk, some yoga anything at all is better than nothing, again no need to start some massive over the top fitness plan, same as food try a few things, you may like weights and resistance training, find a good PT at your height the chances are you'll be great at that as you have small levers, and have a big advantage doing lifting but try lots of things and see what you enjoy then you'll have more chance of sticking with it, make sure you can make it work for you.
The mistake people make is drastically changing everything your poor body is shocked, you get hungry and start a cycle of stuffing and feeling guilty.