Hi Debbie welcome to the forum, this has been so beneficial for me as there is so much help, support and encouragement, as Ian says ask any questions someone will usually have an answer but we are all here for you to lean on at any time.
I'm also with L and D, you will with be assessed for 6 months or 1 year depending on your BMI/co-morbidities (my assessment is for 1 year which is up in June) after your assessment period you will see a hospital doctor who will purely assess if he thinks your fit enough for surgery and he will put you forward to have an MDT meeting, meet the surgeon/consultant, see a psychologist and anaesthetic, all of this I (hopefully) will start after June although the did allow me to see Hospital doctor early so it's one less hoop to jump through after June, following this once you have been accepted for surgery I believe it's anything between 4 to 8 months until you have surgery, it is a long journey and there are many hoops to jump through but hopefully it will be worth it. I ate as usual whilst doing my diary as I wanted them to get a true picture of my eating habits. You should start your milk diet after next appointment it is indeed 4 weeks of semi skimmed milk, 4 pints a day, 2 oxo or bovril drinks (to replace electrolytes in your body) and your allowed 3 little pots of sugar free jelly or 1 sachets sugar free jelly made up, 1 multi vitamin and 2 sugar free gums and unlimited free fluids (sugar free or water) I used chicken OXO in hot milk, it's delicious, almost like chicken soup, I also made my sachet of jelly with just 7 fluid ounces of boiling water then made it up to 1 pint with milk Mmmm again delicious, raspberry was my favourite. The reason for this diet is to 1) prove commitment 2) show you can tolerate a high protein diet and 3) to help you lose 5% of your body weight which you must lose before you can continue with the journey, the rest of my assessment period has just been seeing dietician at each appointment, being weigh and talking about what your eating. I lost 8kg on the milk diet and have continued to lose 2 and a half stone but like you I wouldn't be able to maintain this and would eventually put it all back on and more. You do have to keep that 5% weight loss off throughout, the milk diet isn't so bad, I found it better because it removed all food choices, we do have to do it again for 2 weeks (I believe) immediately before surgery as it shrinks the liver, this is important as they need to be able to move the liver during surgery and I've heard that if they get inside and find it hasn't shrunk they will close you up and won't operate
I hope this is of some help to you, I may have forgotten some things but I'm sure others will let you know, they really are a great bunch on here wishing you much luck and look forward to following your journey x