I expressed exclusively for 5 1/2 months with DD1, who would not BF. I have also been diagnosed recently with ME, though the doctor thought I had probably had it for several years before having children.
I had an Ameda Lactaline double pump, used with an expressing bra, so it could be hands free. And yes, you do pretty much sit there like a cow being milked, once you have adjusted the speed/suction controls to your own comfort. My best friend thought it was hilarious. I started out with a single pump (Medela Swing), but it took a very long time to express, which got very tiring. The double pump really made things easier, I found it took less than half the time to express the same amount of milk (it can be used as a single pump if you ever just want to do one side). Try looking at www.expressyourselfmums.co.uk for expressing products and articles on the subject - I found it very useful.
I did express at night for a couple of weeks, until my HV advised me to stop, because I was exhausted. I would express late at night (11-12pm) then leave it till the morning. My boobs were full, and did occasionally leak and get hard, but it was manageable, and better than the exhaustion of having to feed DD1 at night AND express. It also meant I could get a night off if DH did the night feed sometimes.
I was able to build up a good supply of frozen milk quite quickly, by expressing more than I needed each time, which increased my supply. This also meant I could keep up with DD's increasing appetite, a bit like you would naturally do with BF. You can get the freezer bags from some branches of Boots, or online. I defrosted the bags in water before warming them up to drinking temperature. By 5 1/2 months I had so much frozen milk that I gave up expressing, and just used EBM for a couple of weeks while transitioning to FF at 6 months. I would keep up to a days supply of milk in the fridge ready to warm up too, I always tried to keep one or two feeds ahead, so I wasn't having to express in order to feed.
With DD2 I did breastfeed. I don't know how bad your ME symptoms are, probably worse than mine if you've been advised against BF, but I found BF manageable. To be honest, I felt it was a bit swings and roundabouts with BF and expressing, still not sure which I preferred. I felt I did get more rest with expressing, because DH could do some of the feeding, but there was obviously all the pump and bottle washing to do as well. With expressing, I could see how much milk DD was having, like you can with formula, so it was easier to make sure she was offered a regular amount, which possibly made her sleeping patterns more reliable. BF obviously had the advantage of no planning ahead if going out with DD, and no washing up, but no chance to pass the feeding duty to DH once in a while! I was lucky that both my DDs slept at night, and within about 2 weeks were only having one night feed. I did give DD2 the occasional bottle of EBM once she was a couple of months old, using the Tommee Tippee Closer to Nature bottles, and she had no problems changing from breast to bottle and back again.
Sorry for the essay. Good luck deciding what to do - you have lots of time.