I was not prescribed a liquid diet. I guess you could say my doctor tolerated it...he did not support it. I did it by choice and for two months "ate" only canned liquid diet diet and apart from that, drank only water. This is 100% possible and if you have the right mindset you will not be miserable. I still cooked for my husband every day, and went out to dinner with my husband and friends. I just brought the can. I kind of enjoyed it... Not having to sit down and eat freed up quite a lot of time.
The best I have ever felt in the past 2 years is when I was on the cans alone. It took a few weeks and then I felt great. Obviously when you're not feeling well, knowing the cans help makes it easier to stay on track. After you've been feeling good for a while, that's when it becomes harder to resist "cheating." I did not cheat once and it's something I'm proud of
There are two kinds of liquid diets... elemental (or semi-elemental) and polymeric. Polymeric diets taste better and are much less expensive. Some studies have shown they are about as effective. If (like me) your insurance will not cover the diet, try a polymeric one first rather than pay all the $$$. I have used Nestle Nutrition products: Peptamen 1.5, which is semi-elemental, and Nutren 1.5/2.0 which is polymeric. I buy it off Ebay. If you know someone who works at a hospital, they may be able to buy it for you at cost from the hospital pharmacy. Stay away from Ensure, too much sugar.
Expect to brush your teeth often...and buy a tongue scraper. The stuff coats your mouth.
If your doctor is from the UK, he might also be familiar with elimination diets. The best thing you could do is to go on the liquid diet and then follow a elimination diet--this might help to find out what is triggering your flares. Unfortunately I did not have this kind of support, and once I started back on food, I did not have a very long-lasting remission and ended up on Entocort for a while. Nowadays I still have a can for one meal out of the day and when I have a bad day I go back on cans exclusively for a day or so.
If you have any specific questions, I'm happy to answer.