Where do you take a man on a date?

Seriously, I'm asking.

After a conversation with The Mister yesterday I've decided to take him on a date. It's a way for us both to go out and do something and it's also a bit of a way to say thanks for everything he's done to help me lately. I've been getting more and more crap news from the doctor with every visit and he's been right there still when I've needed him.

So, yeah, it's a sweet idea. Problem is that I have no idea where or what to do. I've been trying to go with things I know he loves in order to piece together a great day, but nothing seems to be working out properly.
His first love is guitars and music, but all those kind of events finished way back in June and no music museum seems to focus much on them. I had the idea of taking him to one of the biggest Gibson retailers in London then going off for a picnic somewhere but it doesn't sound that good.

He also loves food, so I thought about maybe going to borough market next week because he keeps nagging on about it. Problem with that is I'm planning to cook and he'll go mad and buy things to eat therefore he'll ruin my surprise.

He likes theatre but I can't find anything decent and cheap/free.
He likes history but not the kind you can find in an ordinary museum.

ARGGGGHHHHH!!! GOING MAD!!!