Birthday plans- he said he's not fussed?

So my partners birthday is next month and I thought we always talk about visiting national space centre near us but haven't done it so why not as a birthday plan? He's got the day booked off will be his first Saturday off in ages.

I mentioned it to him and he went "oh yeah could do" he didn't seem too keen. He also said not to buy him what he asked for a present if I was gonna book us tickets to go to the centre because money (the gift he asked for costs £80, and the centre tickets will cost roughly £30 so I can understand his concern though I'm pulling in some overtime at work to help.

I mentioned it to him again just now and he just kept saying he's not fussed so I'm not sure whether or not i should because he just kept going I'm not fussed I don't mind. Last year he had a birthday meal which he was really looking forward to and kept talking about so I know he can get excited so I'm thinking maybe he wants something else? I even said do you want something but just don't want to have to plan it? "I don't mind I'm not fussed! I'm not fussy!" Was what I got back. Should I just book the space centre tickets or rethink plans?

(Also if anyone questioning why the national space centre: we both have interests in space we watch videos from kurzgesagt on YouTube together they do really cool science videos deffo recommend watching! And we often talk about that sort of thing)