Of course. Unfortunately I wasn't able to have a PET scan imminently before treatment started, I had one two months prior as an inpatient in hospital which showed stage 2 (this was before I was diagnosed with a 2nd biopsy but they pre warned me it was likely HL). My consultant said that by the time I started treatment I was probably closer to stage 3 but hard to tell as I had glandular fever simultaneously. 

Intermittent fasting has worked great for me, I try to maintain a balanced and healthy diet Mon-Fri and ensure I always take my vitamins every day to try and aid my immune system. I think its important to still remember to treat yourself so don't completely cut all of your favourite treats and snacks out, its a tough journey and you need some pickmeups every now and then! Foods that aid your immune system are great, as ABVD really hits your immune system and you'll be prone to illnesses and viruses etc. Just be wary that ABVD causes food/drink aversions, some foods or drinks that you have around the time of treatment, you may not be able to have again. It's hard to explain but its like a mental block and thinking about the foods makes you feel nauseous. So make sure you don't have your favourite foods near treatment. 

I am sure your nurse specialist and consultant will tell you all about this prior to treatment anyway but I'll try and share some tips from my own experience that work for me. You'll probably be offered a PICC line, I strongly advise it, its a pain living with it for the first few weeks but you get used to it. It makes it much easier to take bloods, administer treatment etc, less needles is always a good thing! I always take chewing gum with me to my treatments, some people take boiled sweets etc too, some of the treatments can have a taste to them and this disguises it nicely for me. ABVD can take anywhere from 1.5hrs to 3hrs, sometimes you'll arrive and the treatment wont be there from pharmacy yet or there'll be other issues and delays, thats just the nature of the NHS, once the treatment starts its usually 90 mins until you're on your way home again. It's important to monitor your temperature so make sure you have a thermometer, take it every day and make sure you're within normal range. One thing I wasn't made aware of prior to treatment is that some of the treatment can cause some reactions in your body for up to 7 hours post treatment, shivering, sickness, aches and pains etc, I was told that as long as my temperature was within normal range this was okay. After I experienced this I was given an anti-histamine prior to treatment by the nurses and its helped ease this.

As im sure you've read online ABVD is usually 6 cycles, 12 treatments, each cycle has part A and part B which are given two weeks apart. After 2 cycles (4 treatments) you'll have another scan to see how things are progressing and then an MDT will review it and decide whether to continue on that plan or change you to an alternative (theres a few different ones). They use something called deauville score to determine if treatment is working, basically a score of 1-3 means treatment is working, 4-5 they may need to escalate things. But each case is unique. If things are moving along nicely they will likely drop the B part of the treatment and you'll continue with just AVD.

I apologise for the information overload! I'm from a medical background in the NHS and these are some things I wish I knew before starting, I apologise if its too much. As I said, you will get through this, treatments have a great success rate and with the support of friends, family and your medical team you'll be great! 

You've got this!