I'm not really sure how to bring the conversation up with him tbh.
Ok, I think we should now focus on helping the op to decide what to say to him about his offer.
Firstly, to re open the conversation about how much he contributes, I think you could say that you've been thinking about it, and are deeply unhappy with the amount as:-
- it doesn't even begin to cover the additional costs of him living there, and
- you feel like you're the one paying his debts back as he's proposing to live virtually free in your household. You're not his mother and £34.61 a week is a derisory sum that wouldn't even cover his food!
- it makes you feel used, and like a complete mug, and you've been here before with your ex. It's very very disrespectful of him, and you won't allow yourself to be used by him in this way. Also, that it was very presumptuous of him to just 'announce' what he would contribute without any discussion.
- Make it very clear that the arrangement must be a win win situation for both of you, not just him! (see comment from a previous poster who talked about 'win win')
Look back on all these comments and work out all your costs for him to see-there was a complicated but very fair calculation that someone wrote early on, about how to work out a fair shared household budget. Use this as a base line- write it down and give it to him. Tell us what he says.
Don't agree anything straight away. Give yourself time to think, and tell him you'll mull over his proposals and get back to him.
You really have to be careful here. Nowhere have you talked about him moving in with you as a sign of an increased commitment between the both of you, and wanting to take your relationship to the next level. It really does sound as though it is sheer convenience on his part while he clears his debts (and probably saves a nice pot for himself) before moving out again, or even actually finishing the relationship)
Don't be embarrassed to talk to him about money, and don't let him tell you that you're 'grabby' either- you're not!
Hopefully, other posters will be along soon to give you some more ideas about what to say to him too.
Sorry this is such a long post- I'm incensed on your behalf!