You can book free bowling for up to 24 people for all day Monday and all day Tuesday- (offer available until 9th February) booking fee applies of 50p. There is no limit (to my knowledge) on the number of games you can book. As long as you do seperate transactions. There appears to be limited availability.
Offer applies at all bowling centres listed on tenpin.co.uk
How to book- follow the link, go to bookings, click on either Monday/Tuesday. It will come up with a price, ignore that, and still click on this. Then it gives you the option of number of bowlers and number of games. Make sure you select the games which cost £0.00. Registration is obviously needed. No extra cost of shoe hire.