Hi there sorry to hear about your situation, sounds a bit like mine last year.  I had a hysterectomy to treat uterine cancer and had to be off work for almost three months because of it. I was on ssp, about £114 a week and I got a similar wage to you so I’m guessing it’ll be the same? I was probably earning less than you tbf. I tried to claim UC but didn’t get anything other than the initial payment. They were clawing back about £40 a month from when I claimed a couple of years ago after a redundancy so you might get something. 
Macmillan benefits advisor told me I would get a work capability form but was wrong, I wasn’t off sick for long enough. I think I learnt that’s for three months or more, would need to check though. Macmillan gave me a £200 grant, don’t know if that’s something you can apply for. And I got a 50% reduction for one month in my council tax so see what your local council can offer. Definitely had to rely on credit card a bit. I’d see if any of your utilities suppliers offer relief for people in your situation. Or can you get a rent/mortgage holiday? 
good luck for your op hope it all goes well and your money stresses ease!