If he likes cars there are some good racing packages about.
My ex had a fab day at the Everyman circuit near Loughborough as a 30th present from his parents and brother.
Quad biking is another idea. I took the ex to Chill Factor in Manchester for a introductory skiing and climbing session which he loved. Something you can both do as well.
A variation on Jenna's good ideas would be to hire a classic / luxury car. I hired an E- tpe Jag for my husbands 30th and had a great day out with him.
Obviously im not sure of his taste in films tv etc but Spamalot is a great show to see at the West End. You can get cheap hotels on Last Minute for London if you stay away from centre.
My Boyf also had a great day at the Everyman circuit.
I often use Tesco vouchers for 4* hotel stays. You change them onlne for their DEALS and they are worth 4 x their face value....I have been to several great Marrioott Hotela (there are several others as well) and you can also change vouchers for restaurants like La Tasca (Spanish Tapas) and Bella Italia....you pay only for drinks! Its really worth doing this and you can see the local sights of the area that you are stayin in.
Just a thought and you may not have Tesco vouchers!!
Whatever u do - have a great time!!
check out what shows/concerts are in a are close to you and treat him with tickets and a night in a hotel for the two of you. Doubles up as a dirty weekend away too!