Erm, just because you pay for something, it doesn't make it "a proper go". There are reasons why criteria are in place. The heavier you are the harder it is to adequately stimulate your ovaries. If it's difficult to stimulate your ovaries then your eggs won't be as good quality. If your eggs aren't as good quality then, donor sperm or no donor sperm, the chances are that any potential embryos won't be as good as they could be. And that's just looking at quality - you need to look at quantity too.
At 33 you have got time on your side to lose weight, for him to "do his thing" and for you both to make every effort to be as fit and healthy as possible.
And if you think that procuring donor sperm is easy then tbh you can think again. There is a massive, massive shortage in the UK - an awful lot is imported. If his motility is sufficient then you will have just as good a chance of conceiving with ICSI as you would with IVF. In which case, why would you even consider donor sperm?
You need to take a step back. You need to decide whether having a child is important enough for you to bust a fucking gut, lose weight, discuss options with DP and stop going off on tangents. It is hard. I can't pretend otherwise. Physically, emotionally, mentally - and financially, even if you do qualify for nhs funding. To say it is a roller coaster is one of the biggest under statements ever.
Do what you need to do, have discussions with the experts, take their advice. Thinking about donor sperm and affairs and "proper goes" is a complete waste of energy and does nothing but add to your list of unanswered questions. Talk to DP as a priority, decide what you want to do and get yourselves into the strongest position you can.